Src kinase-associated phosphoprotein 1 Pleckstrin homology (PH) domain; Adaptor protein Skap1 (also called Skap55/Src kinase-associated phosphoprotein of 55 kDa) and its partner, ADAP (adhesion and degranulation promoting adapter protein) help reorganize the cytoskeleton and/or promote integrin-mediated adhesion upon immunoreceptor activation. Skap1 is also involved in T Cell Receptor (TCR)-induced RapL-Rap1 complex formation and LFA-1 activation. Skap1 has an N-terminal coiled-coil conformation which is proposed to be involved in homodimer formation, a central PH domain and a C-terminal SH3 domain that associates with ADAP. The Skap1 PH domain plays a role in controlling integrin function via recruitment of ADAP-SKAP complexes to integrins as well as in controlling the ability of ADAP to interact with the CBM signalosome and regulate NF-kappaB. SKAP1 is necessary for RapL binding to membranes in a PH domain-dependent manner and the PI3K pathway. Skap adaptor proteins couple receptors to cytoskeletal rearrangements. Skap55/Skap1, Skap2, and Skap-homology (Skap-hom) have an N-terminal coiled-coil conformation, a central PH domain and a C-terminal SH3 domain. Their PH domains bind 3'-phosphoinositides as well as directly affecting targets such as in Skap55 where it directly affecting integrin regulation by ADAP and NF-kappaB activation or in Skap-hom where the dimerization and PH domains comprise a 3'-phosphoinositide-gated molecular switch that controls ruffle formation. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076 108 VIKQGYLEKKSKDHSFFGSEWQKRWCVVSRGLFYYYANEKSKQPKGTFLIKGYGVRMAPHLRRDSKKESCFELTSQDRRS 187
Cdd:cd13380    1 ILKQGYLEKRSKDHSFFGSEWQKRWCVLTNRAFYYYASEKSKQPKGGFLIKGYSAQMAPHLRKDSRRDSCFELTTPGRRT 80

                         90       100
                 ....*....|....*....|....*.
gi 115527076 188 YEFTATSPAEARDWVDQISFLLKDLS 213
Cdd:cd13380   81 YQFTAASPSEARDWVDQIQFLLKDTQ 106

Src kinase-associated phosphoprotein 1 Pleckstrin homology (PH) domain; Adaptor protein Skap1 (also called Skap55/Src kinase-associated phosphoprotein of 55 kDa) and its partner, ADAP (adhesion and degranulation promoting adapter protein) help reorganize the cytoskeleton and/or promote integrin-mediated adhesion upon immunoreceptor activation. Skap1 is also involved in T Cell Receptor (TCR)-induced RapL-Rap1 complex formation and LFA-1 activation. Skap1 has an N-terminal coiled-coil conformation which is proposed to be involved in homodimer formation, a central PH domain and a C-terminal SH3 domain that associates with ADAP. The Skap1 PH domain plays a role in controlling integrin function via recruitment of ADAP-SKAP complexes to integrins as well as in controlling the ability of ADAP to interact with the CBM signalosome and regulate NF-kappaB. SKAP1 is necessary for RapL binding to membranes in a PH domain-dependent manner and the PI3K pathway. Skap adaptor proteins couple receptors to cytoskeletal rearrangements. Skap55/Skap1, Skap2, and Skap-homology (Skap-hom) have an N-terminal coiled-coil conformation, a central PH domain and a C-terminal SH3 domain. Their PH domains bind 3'-phosphoinositides as well as directly affecting targets such as in Skap55 where it directly affecting integrin regulation by ADAP and NF-kappaB activation or in Skap-hom where the dimerization and PH domains comprise a 3'-phosphoinositide-gated molecular switch that controls ruffle formation. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076 108 VIKQGYLEKKSKDHSFFGSEWQKRWCVVSRGLFYYYANEKSKQPKGTFLIKGYGVRMAPHLRRDSKKESCFELTSQDRRS 187
Cdd:cd13380    1 ILKQGYLEKRSKDHSFFGSEWQKRWCVLTNRAFYYYASEKSKQPKGGFLIKGYSAQMAPHLRKDSRRDSCFELTTPGRRT 80

                         90       100
                 ....*....|....*....|....*.
gi 115527076 188 YEFTATSPAEARDWVDQISFLLKDLS 213
Cdd:cd13380   81 YQFTAASPSEARDWVDQIQFLLKDTQ 106

Pleckstrin homology domain; Domain commonly found in eukaryotic signalling proteins. The domain family possesses multiple functions including the abilities to bind inositol phosphates, and various proteins. PH domains have been found to possess inserted domains (such as in PLC gamma, syntrophins) and to be inserted within other domains. Mutations in Brutons tyrosine kinase (Btk) within its PH domain cause X-linked agammaglobulinaemia (XLA) in patients. Point mutations cluster into the positively charged end of the molecule around the predicted binding site for phosphatidylinositol lipids.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076   108 VIKQGYLEKKSKDhsfFGSEWQKRWCVVSRGLFYYYANEKSKQ---PKGTFLIKGYGVRMAPHlRRDSKKESCFELTSQD 184
Cdd:smart00233   1 VIKEGWLYKKSGG---GKKSWKKRYFVLFNSTLLYYKSKKDKKsykPKGSIDLSGCTVREAPD-PDSSKKPHCFEIKTSD 76

                           90       100
                   ....*....|....*....|....*.
gi 115527076   185 RRSYEFTATSPAEARDWVDQISFLLK 210
Cdd:smart00233  77 RKTLLLQAESEEEREKWVEALRKAIA 102

Src homology 3 domains; Src homology 3 (SH3) domains bind to target proteins through sequences containing proline and hydrophobic amino acids. Pro-containing polypeptides may bind to SH3 domains in 2 different binding orientations.

                           10        20        30        40        50
                   ....*....|....*....|....*....|....*....|....*....|....*
gi 115527076   297 YYQGLWDCHGDQPDELSFQRGDLIRILSKEYNmyGWWVGELNSL-VGIVPKEYLT 350
Cdd:smart00326   4 QVRALYDYTAQDPDELSFKKGDIITVLEKSDD--GWWKGRLGRGkEGLFPSNYVE 56

Src kinase-associated phosphoprotein 1 Pleckstrin homology (PH) domain; Adaptor protein Skap1 (also called Skap55/Src kinase-associated phosphoprotein of 55 kDa) and its partner, ADAP (adhesion and degranulation promoting adapter protein) help reorganize the cytoskeleton and/or promote integrin-mediated adhesion upon immunoreceptor activation. Skap1 is also involved in T Cell Receptor (TCR)-induced RapL-Rap1 complex formation and LFA-1 activation. Skap1 has an N-terminal coiled-coil conformation which is proposed to be involved in homodimer formation, a central PH domain and a C-terminal SH3 domain that associates with ADAP. The Skap1 PH domain plays a role in controlling integrin function via recruitment of ADAP-SKAP complexes to integrins as well as in controlling the ability of ADAP to interact with the CBM signalosome and regulate NF-kappaB. SKAP1 is necessary for RapL binding to membranes in a PH domain-dependent manner and the PI3K pathway. Skap adaptor proteins couple receptors to cytoskeletal rearrangements. Skap55/Skap1, Skap2, and Skap-homology (Skap-hom) have an N-terminal coiled-coil conformation, a central PH domain and a C-terminal SH3 domain. Their PH domains bind 3'-phosphoinositides as well as directly affecting targets such as in Skap55 where it directly affecting integrin regulation by ADAP and NF-kappaB activation or in Skap-hom where the dimerization and PH domains comprise a 3'-phosphoinositide-gated molecular switch that controls ruffle formation. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076 108 VIKQGYLEKKSKDHSFFGSEWQKRWCVVSRGLFYYYANEKSKQPKGTFLIKGYGVRMAPHLRRDSKKESCFELTSQDRRS 187
Cdd:cd13380    1 ILKQGYLEKRSKDHSFFGSEWQKRWCVLTNRAFYYYASEKSKQPKGGFLIKGYSAQMAPHLRKDSRRDSCFELTTPGRRT 80

                         90       100
                 ....*....|....*....|....*.
gi 115527076 188 YEFTATSPAEARDWVDQISFLLKDLS 213
Cdd:cd13380   81 YQFTAASPSEARDWVDQIQFLLKDTQ 106

Src kinase-associated phosphoprotein homolog and Skap 2 Pleckstrin homology (PH) domain; Adaptor protein Skap-hom, a homolog of Skap55, which interacts with actin and with ADAP (adhesion and degranulation promoting adapter protein) undergoes tyrosine phosphorylation in response to plating of bone marrow-derived macrophages on fibronectin. Skap-hom has an N-terminal coiled-coil conformation that is involved in homodimer formation, a central PH domain and a C-terminal SH3 domain that associates with ADAP. The Skap-hom PH domain regulates intracellular targeting; its interaction with the DM domain inhibits Skap-hom actin-based ruffles in macrophages and its binding to 3'-phosphoinositides reverses this autoinhibition. The Skap-hom PH domain binds PI[3,4]P2 and PI[3,4,5]P3, but not to PI[3]P, PI[5]P, or PI[4,5]P2. Skap2 is a downstream target of Heat shock transcription factor 4 (HSF4) and functions in the regulation of actin reorganization during lens differentiation. It is thought that SKAP2 anchors the complex of tyrosine kinase adaptor protein 2 (NCK20/focal adhesion to fibroblast growth factor receptors at the lamellipodium in lens epithelial cells. Skap2 has an N-terminal coiled-coil conformation which interacts with the SH2 domain of NCK2, a central PH domain and a C-terminal SH3 domain that associates with ADAP (adhesion and degranulation promoting adapter protein)/FYB (the Fyn binding protein). Skap2 PH domain binds to membrane lipids. Skap adaptor proteins couple receptors to cytoskeletal rearrangements. Src kinase-associated phosphoprotein of 55 kDa (Skap55)/Src kinase-associated phosphoprotein 1 (Skap1), Skap2, and Skap-hom have an N-terminal coiled-coil conformation, a central PH domain and a C-terminal SH3 domain. Their PH domains bind 3'-phosphoinositides as well as directly affecting targets such as in Skap55 where it directly affecting integrin regulation by ADAP and NF-kappaB activation or in Skap-hom where the dimerization and PH domains comprise a 3'-phosphoinositide-gated molecular switch that controls ruffle formation. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076 108 VIKQGYLEKKSKDHSFFGSEWQKRWCVVSRGLFYYYANEKSKQPKGTFLIKGYGVRMAPHLRRDSKKESCFELTSQDRRS 187
Cdd:cd13381    1 VLKAGYLEKRRKDHSFFGFEWQKRWCALSNSVFYYYGSDKDKQQKGEFAIDGYDVKMNNTLRKDAKKDCCFEICAPDKRV 80

                         90       100
                 ....*....|....*....|....*
gi 115527076 188 YEFTATSPAEARDWVDQISFLLKDL 212
Cdd:cd13381   81 YQFTAASPKEAEEWVQQIKFILQDL 105

Src Homology 3 domain of Src Kinase-Associated Phosphoprotein 2; SKAP2, also called SKAP55-Related (SKAP55R) or SKAP55 homolog (SKAP-HOM or SKAP55-HOM), is an immune cell-specific adaptor protein that plays an important role in adhesion and migration of B-cells and macrophages. Binding partners include ADAP (adhesion and degranulation-promoting adaptor protein), YopH, SHPS1, and HPK1. SKAP2 has also been identified as a substrate for lymphoid-specific tyrosine phosphatase (Lyp), which has been implicated in a wide variety of autoimmune diseases. It contains a pleckstrin homology (PH) domain, a C-terminal SH3 domain, and several tyrosine phosphorylation sites. Like SKAP1, SKAP2 is expected to bind primarily to a proline-rich region of ADAP through its SH3 domain; its degradation may be regulated by ADAP. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 115527076 297 YYQGLWDCHGDQPDELSFQRGDLIRILSKEYNMYGWWVGELNSLVGIVPKEYL 349
Cdd:cd12045    1 FYQGLWDCTGDQPDELSFKRGDTIYILSKEYNRFGWWVGEMKGTIGLVPKAYI 53

Pleckstrin homology domain; Domain commonly found in eukaryotic signalling proteins. The domain family possesses multiple functions including the abilities to bind inositol phosphates, and various proteins. PH domains have been found to possess inserted domains (such as in PLC gamma, syntrophins) and to be inserted within other domains. Mutations in Brutons tyrosine kinase (Btk) within its PH domain cause X-linked agammaglobulinaemia (XLA) in patients. Point mutations cluster into the positively charged end of the molecule around the predicted binding site for phosphatidylinositol lipids.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076   108 VIKQGYLEKKSKDhsfFGSEWQKRWCVVSRGLFYYYANEKSKQ---PKGTFLIKGYGVRMAPHlRRDSKKESCFELTSQD 184
Cdd:smart00233   1 VIKEGWLYKKSGG---GKKSWKKRYFVLFNSTLLYYKSKKDKKsykPKGSIDLSGCTVREAPD-PDSSKKPHCFEIKTSD 76

                           90       100
                   ....*....|....*....|....*.
gi 115527076   185 RRSYEFTATSPAEARDWVDQISFLLK 210
Cdd:smart00233  77 RKTLLLQAESEEEREKWVEALRKAIA 102

PH domain; PH stands for pleckstrin homology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076  108 VIKQGYLEKKSKDhsfFGSEWQKRWCVVSRGLFYYYANE---KSKQPKGTFLIKGYGVRMAPHLrRDSKKESCFELTSQD 184
Cdd:pfam00169   1 VVKEGWLLKKGGG---KKKSWKKRYFVLFDGSLLYYKDDksgKSKEPKGSISLSGCEVVEVVAS-DSPKRKFCFELRTGE 76

                          90       100
                  ....*....|....*....|....*....
gi 115527076  185 R---RSYEFTATSPAEARDWVDQISFLLK 210
Cdd:pfam00169  77 RtgkRTYLLQAESEEERKDWIKAIQSAIR 105

Phosphoinositol 3-phosphate binding proteins 1, 2, and 3 pleckstrin homology (PH) domain; PEPP1 (also called PLEKHA4/PH domain-containing family A member 4 and RHOXF1/Rhox homeobox family member 1), and related homologs PEPP2 (also called PLEKHA5/PH domain-containing family A member 5) and PEPP3 (also called PLEKHA6/PH domain-containing family A member 6), have PH domains that interact specifically with PtdIns(3,4)P3. Other proteins that bind PtdIns(3,4)P3 specifically are: TAPP1 (tandem PH-domain-containing protein-1) and TAPP2], PtdIns3P AtPH1, and Ptd- Ins(3,5)P2 (centaurin-beta2). All of these proteins contain at least 5 of the 6 conserved amino acids that make up the putative phosphatidylinositol 3,4,5- trisphosphate-binding motif (PPBM) located at their N-terminus. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076 105 LDNVIKQGYLEKKSkdhsffGS---EWQKRWCVVSRGLFYYYANEKSKQPKGTFLIKGYGVRMAPHLRRDSKKEScFELT 181
Cdd:cd13248    4 NAPVVMSGWLHKQG------GSglkNWRKRWFVLKDNCLYYYKDPEEEKALGSILLPSYTISPAPPSDEISRKFA-FKAE 76

                         90       100
                 ....*....|....*....|....*
gi 115527076 182 SQDRRSYEFTATSPAEARDWVDQIS 206
Cdd:cd13248   77 HANMRTYYFAADTAEEMEQWMNAMS 101

Ras-specific guanine nucleotide-releasing factors 1 and 2 Pleckstrin homology (PH) domain; RasGRF1 (also called GRF1; CDC25Mm/Ras-specific nucleotide exchange factor CDC25; GNRP/Guanine nucleotide-releasing protein) and RasGRF2 (also called GRF2; Ras guanine nucleotide exchange factor 2) are a family of guanine nucleotide exchange factors (GEFs). They both promote the exchange of Ras-bound GDP by GTP, thereby regulating the RAS signaling pathway. RasGRF1 and RasGRF2 form homooligomers and heterooligomers. GRF1 has 3 isoforms and GRF2 has 2 isoforms. The longest isoforms of RasGRF1 and RasGRF2 contain the following domains: a Rho-GEF domain sandwiched between 2 PH domains, IQ domains, a REM (Ras exchanger motif) domain, and a Ras-GEF domainwhich gives them the capacity to activate both Ras and Rac GTPases in response to signals from a variety of neurotransmitter receptors. Their IQ domains allow them to act as calcium sensors to mediate the actions of NMDA-type and calcium-permeable AMPA-type glutamate receptors. GRF1 also mediates the action of dopamine receptors that signal through cAMP. GRF1 and GRF2 play strikingly different roles in regulating MAP kinase family members, neuronal synaptic plasticity, specific forms of learning and memory, and behavioral responses to psychoactive drugs. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076 110 KQGYLEKKSKDhsffGSEWQKRWCVVSRGLFYYYANEKSKQPKGTFLIKGYGVRMAPHLRRDSK------KESCFELT-- 181
Cdd:cd13261    7 KRGYLSKKTSD----SGKWHERWFALYQNLLFYFENESSSRPSGLYLLEGCYCERLPTPKGALKgkdhleKQHYFTISfr 82

                         90       100
                 ....*....|....*....|....*
gi 115527076 182 SQDRRSYEFTATSPAEARDWVDQIS 206
Cdd:cd13261   83 HENQRQYELRAETESDCDEWVEAIK 107

Rho GTPase activating protein 25 and related proteins Pleckstrin homology (PH) domain; RhoGAP25 (also called ArhGap25) like other RhoGaps are involved in cell polarity, cell morphology and cytoskeletal organization. They act as GTPase activators for the Rac-type GTPases by converting them to an inactive GDP-bound state and control actin remodeling by inactivating Rac downstream of Rho leading to suppress leading edge protrusion and promotes cell retraction to achieve cellular polarity and are able to suppress RAC1 and CDC42 activity in vitro. Overexpression of these proteins induces cell rounding with partial or complete disruption of actin stress fibers and formation of membrane ruffles, lamellipodia, and filopodia. This hierarchy contains RhoGAP22, RhoGAP24, and RhoGAP25. Members here contain an N-terminal PH domain followed by a RhoGAP domain and either a BAR or TATA Binding Protein (TBP) Associated Factor 4 (TAF4) domain. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076 107 NVIKQGYLEKKSkdhSFFGSeWQKRWCVVSRGLFYYYANEKSKQPKGTFLIKGYGVRMAPHLRRDSKKeSCFELT---SQ 183
Cdd:cd13263    2 RPIKSGWLKKQG---SIVKN-WQQRWFVLRGDQLYYYKDEDDTKPQGTIPLPGNKVKEVPFNPEEPGK-FLFEIIpggGG 76

                         90       100
                 ....*....|....*....|....*..
gi 115527076 184 DRR-----SYEFTATSPAEARDWVDQI 205
Cdd:cd13263   77 DRMtsnhdSYLLMANSQAEMEEWVKVI 103

Connector enhancer of KSR (Kinase suppressor of ras) (CNK) pleckstrin homology (PH) domain; CNK family members function as protein scaffolds, regulating the activity and the subcellular localization of RAS activated RAF. There is a single CNK protein present in Drosophila and Caenorhabditis elegans in contrast to mammals which have 3 CNK proteins (CNK1, CNK2, and CNK3). All of the CNK members contain a sterile a motif (SAM), a conserved region in CNK (CRIC) domain, and a PSD-95/DLG-1/ZO-1 (PDZ) domain, and, with the exception of CNK3, a PH domain. A CNK2 splice variant CNK2A also has a PDZ domain-binding motif at its C terminus and Drosophila CNK (D-CNK) also has a domain known as the Raf-interacting region (RIR) that mediates binding of the Drosophila Raf kinase. This cd contains CNKs from mammals, chickens, amphibians, fish, and crustacea. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076 103 QELDNVIKQGYLEKKSKDHSFFGSEWQKRWCVVSRGLFYYYANEKSKQPKGTFLIKGYGVRMAphlrRDSKKESCFELTS 182
Cdd:cd01260    8 KDLGRGDCQGWLWKKKEAKSFFGQKWKKYWFVLKGSSLYWYSNQQDEKAEGFINLPDFKIERA----SECKKKYAFKACH 83

                         90       100
                 ....*....|....*....|...
gi 115527076 183 QDRRSYEFTATSPAEARDWVDQI 205
Cdd:cd01260   84 PKIKTFYFAAENLDDMNKWLSKL 106

Src Homology 3 domain of SH3 domain-containing protein 21 (SH3D21) and similar proteins; N-terminal SH3 domain of the uncharacterized protein SH3 domain-containing protein 21, and similar uncharacterized domains, it belongs to the CD2AP-like_3 subfamily of proteins. The CD2AP-like_3 subfamily is composed of the third SH3 domain (SH3C) of CD2AP, CIN85 (Cbl-interacting protein of 85 kDa), and similar domains. CD2AP and CIN85 are adaptor proteins that bind to protein partners and assemble complexes that have been implicated in T cell activation, kidney function, and apoptosis of neuronal cells. They also associate with endocytic proteins, actin cytoskeleton components, and other adaptor proteins involved in receptor tyrosine kinase (RTK) signaling. CD2AP and the main isoform of CIN85 contain three SH3 domains, a proline-rich region, and a C-terminal coiled-coil domain. All of these domains enable CD2AP and CIN85 to bind various protein partners and assemble complexes that have been implicated in many different functions. SH3C of both proteins have been shown to bind to ubiquitin. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 115527076 297 YYQGLWDCHGDQPDELSFQRGDLIRILSKEYNMYGWWVGELNSLVGIVPKEYL 349
Cdd:cd12142    1 YCRVLFDYNPVAPDELALKKGDVIEVISKETEDEGWWEGELNGRRGFFPDNFV 53

Third Src Homology 3 domain (SH3C) of CD2-associated protein and similar proteins; This subfamily is composed of the third SH3 domain (SH3C) of CD2AP, CIN85 (Cbl-interacting protein of 85 kDa), and similar domains. CD2AP and CIN85 are adaptor proteins that bind to protein partners and assemble complexes that have been implicated in T cell activation, kidney function, and apoptosis of neuronal cells. They also associate with endocytic proteins, actin cytoskeleton components, and other adaptor proteins involved in receptor tyrosine kinase (RTK) signaling. CD2AP and the main isoform of CIN85 contain three SH3 domains, a proline-rich region, and a C-terminal coiled-coil domain. All of these domains enable CD2AP and CIN85 to bind various protein partners and assemble complexes that have been implicated in many different functions. SH3C of both proteins have been shown to bind to ubiquitin. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*....
gi 115527076 297 YYQGLWDCHGDQPDELSFQRGDLIRILSKEYNMYGWWVGELNSLVGIVP 345
Cdd:cd11875    1 KARVLFDYEAENEDELTLREGDIVTILSKDCEDKGWWKGELNGKRGVFP 49

Fungal proteins Pleckstrin homology (PH) domain, repeat 1; The functions of these fungal proteins are unknown, but they all contain 2 PH domains. This cd represents the first PH repeat. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076 104 ELDNVIKQGYLEKKSKDHSFfgseWQKRWCVVSRGLFYYYANEKSKQPKGTFLIKGYgVRMAPHlrRDSKKESCFELTSQ 183
Cdd:cd13298    2 EFDRVLKSGYLLKRSRKTKN----WKKRWVVLRPCQLSYYKDEKEYKLRRVINLSEL-LAVAPL--KDKKRKNVFGIYTP 74

                         90       100
                 ....*....|....*....|..
gi 115527076 184 DrRSYEFTATSPAEARDWVDQI 205
Cdd:cd13298   75 S-KNLHFRATSEKDANEWVEAL 95

ArfGAP with RhoGAP domain, ankyrin repeat and PH domain Pleckstrin homology (PH) domain, repeat 3; ARAP proteins (also called centaurin delta) are phosphatidylinositol 3,4,5-trisphosphate-dependent GTPase-activating proteins that modulate actin cytoskeleton remodeling by regulating ARF and RHO family members. They bind phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) and phosphatidylinositol 3,4-bisphosphate (PtdIns(3,4,5)P2) binding. There are 3 mammalian ARAP proteins: ARAP1, ARAP2, and ARAP3. All ARAP proteins contain a N-terminal SAM (sterile alpha motif) domain, 5 PH domains, an ArfGAP domain, 2 ankyrin domain, A RhoGap domain, and a Ras-associating domain. This hierarchy contains the third PH domain in ARAP. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076 114 LEKKSKDhsffgsEWQKRWCVVSRGLFYYYANEKSKQPKGTFLIKGYgVRMA---PHLRRDSKKESCFELTSQDRRSYEF 190
Cdd:cd13256   19 LERRARE------EFSRRWCVLEDGFLSYYESERSPEPNGEIDVSEI-VCLAvspPDTHPGDGFPFTFELYLESERLYLF 91

                         90
                 ....*....|....*
gi 115527076 191 TATSPAEARDWVDQI 205
Cdd:cd13256   92 GLETAEALHEWVKAI 106

Autophagy-related protein 26/Sterol 3-beta-glucosyltransferase Pleckstrin homology (PH) domain, repeat 1; ATG26 (also called UGT51/UDP-glycosyltransferase 51), a member of the glycosyltransferase 28 family, resulting in the biosynthesis of sterol glucoside. ATG26 in decane metabolism and autophagy. There are 32 known autophagy-related (ATG) proteins, 17 are components of the core autophagic machinery essential for all autophagy-related pathways and 15 are the additional components required only for certain pathways or species. The core autophagic machinery includes 1) the ATG9 cycling system (ATG1, ATG2, ATG9, ATG13, ATG18, and ATG27), 2) the phosphatidylinositol 3-kinase complex (ATG6/VPS30, ATG14, VPS15, and ATG34), and 3) the ubiquitin-like protein system (ATG3, ATG4, ATG5, ATG7, ATG8, ATG10, ATG12, and ATG16). Less is known about how the core machinery is adapted or modulated with additional components to accommodate the nonselective sequestration of bulk cytosol (autophagosome formation) or selective sequestration of specific cargos (Cvt vesicle, pexophagosome, or bacteria-containing autophagosome formation). The pexophagosome-specific additions include the ATG30-ATG11-ATG17 receptor-adaptors complex, the coiled-coil protein ATG25, and the sterol glucosyltransferase ATG26. ATG26 is necessary for the degradation of medium peroxisomes. It contains 2 GRAM domains and a single PH domain. PH domains are only found in eukaryotes. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. PH domains also have diverse functions. They are often involved in targeting proteins to the plasma membrane, but few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076 106 DNVIKQGYLEKKSKDHSFfgseWQKRWCVVSRGLFYYYANekSKQ---PKGTF-LIKGYGVRMAPHlrrDSKKESCFELT 181
Cdd:cd13215   19 GAVIKSGYLSKRSKRTLR----YTRYWFVLKGDTLSWYNS--STDlyfPAGTIdLRYATSIELSKS---NGEATTSFKIV 89

                         90       100
                 ....*....|....*....|....
gi 115527076 182 SQDRRsYEFTATSPAEARDWVDQI 205
Cdd:cd13215   90 TNSRT-YKFKADSETSADEWVKAL 112

C-terminal Src homology 3 domain of Growth factor receptor-bound protein 2 (GRB2) and related proteins; This family includes the adaptor protein GRB2 and related proteins including Drosophila melanogaster Downstream of receptor kinase (DRK), Caenorhabditis elegans Sex muscle abnormal protein 5 (Sem-5), GRB2-related adaptor protein (GRAP), GRAP2, and similar proteins. Family members contain an N-terminal SH3 domain, a central SH2 domain, and a C-terminal SH3 domain. GRB2/Sem-5/DRK is a critical signaling molecule that regulates the Ras pathway by linking tyrosine kinases to the Ras guanine nucleotide releasing protein Sos (son of sevenless), which converts Ras to the active GTP-bound state. GRAP2 plays an important role in T cell receptor (TCR) signaling by promoting the formation of the SLP-76:LAT complex, which couples the TCR to the Ras pathway. GRAP acts as a negative regulator of T cell receptor (TCR)-induced lymphocyte proliferation by downregulating the signaling to the Ras/ERK pathway. The C-terminal SH3 domains (SH3c) of GRB2 and GRAP2 have been shown to bind to classical PxxP motif ligands, as well as to non-classical motifs. GRB2 SH3c binds Gab2 (Grb2-associated binder 2) through epitopes containing RxxK motifs, while the SH3c of GRAP2 binds to the phosphatase-like protein HD-PTP via a RxxxxK motif. SH3 domains are protein interaction domains that typically bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|..
gi 115527076 299 QGLWDCHGDQPDELSFQRGDLIRILSKEYNmyGWWVGELNSLVGIVPKEYLT 350
Cdd:cd11805    3 QALYDFNPQEPGELEFRRGDIITVLDSSDP--DWWKGELRGRVGIFPANYVQ 52

Switch-associated protein-70 Pleckstrin homology (PH) domain; SWAP-70 (also called Differentially expressed in FDCP 6/DEF-6 or IRF4-binding protein) functions in cellular signal transduction pathways (in conjunction with Rac), regulates cell motility through actin rearrangement, and contributes to the transformation and invasion activity of mouse embryo fibroblasts. Metazoan SWAP-70 is found in B lymphocytes, mast cells, and in a variety of organs. Metazoan SWAP-70 contains an N-terminal EF-hand motif, a centrally located PH domain, and a C-terminal coiled-coil domain. The PH domain of Metazoan SWAP-70 contains a phosphoinositide-binding site and a nuclear localization signal (NLS), which localize SWAP-70 to the plasma membrane and nucleus, respectively. The NLS is a sequence of four Lys residues located at the N-terminus of the C-terminal a-helix; this is a unique characteristic of the Metazoan SWAP-70 PH domain. The SWAP-70 PH domain binds PtdIns(3,4,5)P3 and PtdIns(4,5)P2 embedded in lipid bilayer vesicles. There are additional plant SWAP70 proteins, but these are not included in this hierarchy. Rice SWAP70 (OsSWAP70) exhibits GEF activity toward the its Rho GTPase, OsRac1, and regulates chitin-induced production of reactive oxygen species and defense gene expression in rice. Arabidopsis SWAP70 (AtSWAP70) plays a role in both PAMP- and effector-triggered immunity. Plant SWAP70 contains both DH and PH domains, but their arrangement is the reverse of that in typical DH-PH-type Rho GEFs, wherein the DH domain is flanked by a C-terminal PH domain. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076 107 NVIKQGYLEKKSkdHSFfgSEWQKRWCVVSRGLFYYYANEKSKQPKGTFLIKGYGvRMAPHLRRDSKKesCFELTSQDRR 186
Cdd:cd13273    7 DVIKKGYLWKKG--HLL--PTWTERWFVLKPNSLSYYKSEDLKEKKGEIALDSNC-CVESLPDREGKK--CRFLVKTPDK 79

                         90
                 ....*....|....*....
gi 115527076 187 SYEFTATSPAEARDWVDQI 205
Cdd:cd13273   80 TYELSASDHKTRQEWIAAI 98

Myosin X Pleckstrin homology (PH) domain, repeat 2; MyoX, a MyTH-FERM myosin, is a molecular motor that has crucial functions in the transport and/or tethering of integrins in the actin-based extensions known as filopodia, microtubule binding, and in netrin-mediated axon guidance. It functions as a dimer. MyoX walks on bundles of actin, rather than single filaments, unlike the other unconventional myosins. MyoX is present in organisms ranging from humans to choanoflagellates, but not in Drosophila and Caenorhabditis elegans.MyoX consists of a N-terminal motor/head region, a neck made of 3 IQ motifs, and a tail consisting of a coiled-coil domain, a PEST region, 3 PH domains, a myosin tail homology 4 (MyTH4), and a FERM domain at its very C-terminus. The first PH domain in the MyoX tail is a split-PH domain, interupted by the second PH domain such that PH 1a and PH 1b flanks PH 2. The third PH domain (PH 3) follows the PH 1b domain. This cd contains the second PH repeat. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076 110 KQGYLEKKSKDHSFFG-SEWQKRWCVVSRGLFYYYAN-EKSKQPKGTFlikgyGVRMAPHLRRDSKKESCFELTSQDRrS 187
Cdd:cd13296    1 KSGWLTKKGGGSSTLSrRNWKSRWFVLRDTVLKYYENdQEGEKLLGTI-----DIRSAKEIVDNDPKENRLSITTEER-T 74

                         90
                 ....*....|....*....
gi 115527076 188 YEFTATSPAEARDWVDQIS 206
Cdd:cd13296   75 YHLVAESPEDASQWVNVLT 93

Second Src Homology 3 domain of FCH and double SH3 domains proteins; This group is composed of FCH and double SH3 domains protein 1 (FCHSD1) and FCHSD2. These proteins have a common domain structure consisting of an N-terminal F-BAR (FES-CIP4 Homology and Bin/Amphiphysin/Rvs), two SH3, and C-terminal proline-rich domains. They have only been characterized in silico and their functions remain unknown. This group also includes the insect protein, nervous wreck, which acts as a regulator of synaptic growth signaling. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|.
gi 115527076 297 YYQGLWDCHGDQPDELSFQRGDLIRILSKEYNMY--GWWVGELNSLVGIVP 345
Cdd:cd11762    1 LVRALYDYEAQSDEELSFPEGAIIRILRKDDNGVddGWWEGEFNGRVGVFP 51

Src homology 3 domain of CAS (Crk-Associated Substrate) scaffolding protein family member, Embryonal Fyn-associated Substrate; EFS is also called HEFS, CASS3 (Cas scaffolding protein family member 3) or SIN (Src-interacting protein). It was identified based on interactions with the Src kinases, Fyn and Yes. It plays a role in thymocyte development and acts as a negative regulator of T cell proliferation. CAS proteins function as molecular scaffolds to regulate protein complexes that are involved in many cellular processes. They share a common domain structure that includes an N-terminal SH3 domain, an unstructured substrate domain that contains many YxxP motifs, a serine-rich four-helix bundle, and a FAT-like C-terminal domain. The SH3 domain of CAS proteins binds to diverse partners including FAK, FRNK, Pyk2, PTP-PEST, DOCK180, among others. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*...
gi 115527076 299 QGLWDCHGDQPDELSFQRGDLIRILSKEY-NMYGWWVGELNSLVGIVP 345
Cdd:cd12003    4 KALYDNAAESPEELSFRRGDVLMVLKREHgSLPGWWLCSLHGQQGIAP 51

Dedicator of cytokinesis-D subfamily Pleckstrin homology (PH) domain; DOCK-D subfamily (also called Zizimin subfamily) consists of Dock9/Zizimin1, Dock10/Zizimin3, and Dock11/Zizimin2. DOCK-D has a N-terminal DUF3398 domain, a PH-like domain, a Dock Homology Region 1, DHR1 (also called CZH1), a C2 domain, and a C-terminal DHR2 domain (also called CZH2). Zizimin1 is enriched in the brain, lung, and kidney; zizimin2 is found in B and T lymphocytes, and zizimin3 is enriched in brain, lung, spleen and thymus. Zizimin1 functions in autoinhibition and membrane targeting. Zizimin2 is an immune-related and age-regulated guanine nucleotide exchange factor, which facilitates filopodial formation through activation of Cdc42, which results in activation of cell migration. No function has been determined for Zizimin3 to date. The N-terminal half of zizimin1 binds to the GEF domain through three distinct areas, including CZH1, to inhibit the interaction with Cdc42. In addition its PH domain binds phosphoinositides and mediates zizimin1 membrane targeting. DOCK is a family of proteins involved in intracellular signalling networks. They act as guanine nucleotide exchange factors for small G proteins of the Rho family, such as Rac and Cdc42. There are 4 subfamilies of DOCK family proteins based on their sequence homology: A-D. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076 108 VIKQGYLEKKSKDHSFFGS-----EWQKRWCVVSR---GLFY--YYANEKSKQPKGT-FLIKGYGVRMAPHLRRdskkeS 176
Cdd:cd13267    6 ITKEGYLYKGPENSSDSFIslamkSFKRRFFHLKQlvdGSYIleFYKDEKKKEAKGTiFLDSCTGVVQNSKRRK-----F 80

                         90       100
                 ....*....|....*....|....*.
gi 115527076 177 CFELTSQDRRSYEFTATSPAEARDWV 202
Cdd:cd13267   81 CFELRMQDKKSYVLAAESEAEMDEWI 106

N-terminal Src homology 3 domain of Growth factor receptor-bound protein 2; GRB2 is a critical signaling molecule that regulates the Ras pathway by linking tyrosine kinases to the Ras guanine nucleotide releasing protein Sos (son of sevenless), which converts Ras to the active GTP-bound state. It is ubiquitously expressed in all tissues throughout development and is important in cell cycle progression, motility, morphogenesis, and angiogenesis. In lymphocytes, GRB2 is associated with antigen receptor signaling components. GRB2 contains an N-terminal SH3 domain, a central SH2 domain, and a C-terminal SH3 domain. Its N-terminal SH3 domain binds to Sos and Sos-derived proline-rich peptides. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|
gi 115527076 310 DELSFQRGDLIRILSKEYNMyGWWVGELNSLVGIVPKEYL 349
Cdd:cd11946   15 DELSFKRGDILKVLNEECDQ-NWYKAELNGKDGFIPKNYI 53

ArfGAP with coiled-coil, ankyrin repeat and PH domains Pleckstrin homology (PH) domain; ACAP (also called centaurin beta) functions both as a Rab35 effector and as an Arf6-GTPase-activating protein (GAP) by which it controls actin remodeling and membrane trafficking. ACAP contain an NH2-terminal bin/amphiphysin/Rvs (BAR) domain, a phospholipid-binding domain, a PH domain, a GAP domain, and four ankyrin repeats. The AZAPs constitute a family of Arf GAPs that are characterized by an NH2-terminal pleckstrin homology (PH) domain and a central Arf GAP domain followed by two or more ankyrin repeats. On the basis of sequence and domain organization, the AZAP family is further subdivided into four subfamilies: 1) the ACAPs contain an NH2-terminal bin/amphiphysin/Rvs (BAR) domain (a phospholipid-binding domain that is thought to sense membrane curvature), a single PH domain followed by the GAP domain, and four ankyrin repeats; 2) the ASAPs also contain an NH2-terminal BAR domain, the tandem PH domain/GAP domain, three ankyrin repeats, two proline-rich regions, and a COOH-terminal Src homology 3 domain; 3) the AGAPs contain an NH2-terminal GTPase-like domain (GLD), a split PH domain, and the GAP domain followed by four ankyrin repeats; and 4) the ARAPs contain both an Arf GAP domain and a Rho GAP domain, as well as an NH2-terminal sterile-a motif (SAM), a proline-rich region, a GTPase-binding domain, and five PH domains. PMID 18003747 and 19055940 Centaurin can bind to phosphatidlyinositol (3,4,5)P3. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 115527076 110 KQGYLEKKSkdHSFFGSeWQKRWCVVSRGLFYYYANEKSKQPKgtflikgygvRMAPHLRRDSKKES-------CFELTS 182
Cdd:cd13250    1 KEGYLFKRS--SNAFKT-WKRRWFSLQNGQLYYQKRDKKDEPT----------VMVEDLRLCTVKPTedsdrrfCFEVIS 67

                         90       100
                 ....*....|....*....|...
gi 115527076 183 QDrRSYEFTATSPAEARDWVDQI 205
Cdd:cd13250   68 PT-KSYMLQAESEEDRQAWIQAI 89

Src Homology 3 domain of Mixed Lineage Kinases; MLKs are Serine/Threonine Kinases (STKs), catalyzing the transfer of the gamma-phosphoryl group from ATP to S/T residues on protein substrates. MLKs act as mitogen-activated protein kinase kinase kinases (MAP3Ks, MKKKs, MAPKKKs), which phosphorylate and activate MAPK kinases (MAPKKs or MKKs or MAP2Ks), which in turn phosphorylate and activate MAPKs during signaling cascades that are important in mediating cellular responses to extracellular signals. MLKs play roles in immunity and inflammation, as well as in cell death, proliferation, and cell cycle regulation. Mammals have four MLKs (MLK1-4), mostly conserved in vertebrates, which contain an SH3 domain, a catalytic kinase domain, a leucine zipper, a proline-rich region, and a CRIB domain that mediates binding to GTP-bound Cdc42 and Rac. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|..
gi 115527076 302 WDCHGDqpDELSFQRGDLIRILSKEYNMYG---WWVGELNSLVGIVPKEYLT 350
Cdd:cd11876    8 YDARGE--DELTLRRGQPVEVLSKDAAVSGdegWWTGKIGDKVGIFPSNYVA 57

Second Src Homology 3 domain of FCH and double SH3 domains protein 2; FCHSD2 has a domain structure consisting of an N-terminal F-BAR (FES-CIP4 Homology and Bin/Amphiphysin/Rvs), two SH3, and C-terminal proline-rich domains. It has only been characterized in silico and its function is unknown. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|
gi 115527076 297 YYQGLWDCHGDQPDELSFQRGDLIRILSKEYNM-YGWWVGELNSLVGIVP 345
Cdd:cd11894    1 FVKALYDYEGQTDDELSFPEGAIIRILNKENQDdDGFWEGEFNGRIGVFP 50

ArfGAP with SH3 domain, ankyrin repeat and PH domain Pleckstrin homology (PH) domain; ASAPs (ASAP1, ASAP2, and ASAP3) function as an Arf-specific GAPs, participates in rhodopsin trafficking, is associated with tumor cell metastasis, modulates phagocytosis, promotes cell proliferation, facilitates vesicle budding, Golgi exocytosis, and regulates vesicle coat assembly via a Bin/Amphiphysin/Rvs domain. ASAPs contain an NH2-terminal BAR domain, a tandem PH domain/GAP domain, three ankyrin repeats, two proline-rich regions, and a COOH-terminal Src homology 3 (SH3) domain. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

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gi 115527076 110 KQGYLEKKSKdhSFFGSEWQKRWCVVSRGLFYYYANEKSKQPKGTFLIKgygvrMAPHLRRDSKKesCFELTSQDrRSYE 189
Cdd:cd13251   12 KSGYLLKKSE--GKIRKVWQKRRCSIKDGFLTISHADENKPPAKLNLLT-----CQVKLVPEDKK--CFDLISHN-RTYH 81

                         90
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gi 115527076 190 FTATSPAEARDWV 202
Cdd:cd13251   82 FQAEDENDANAWM 94

Variant SH3 domain;

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gi 115527076  309 PDELSFQRGDLIRILSKEYNmyGWWVGELNSLVGIVPKEYLT 350
Cdd:pfam14604  10 DDELSLQRGDVITVIEESED--GWWEGINTGRTGLVPANYVE 49

Src homology 3 domain of CAS (Crk-Associated Substrate) scaffolding proteins; CAS proteins function as molecular scaffolds to regulate protein complexes that are involved in many cellular processes including migration, chemotaxis, apoptosis, differentiation, and progenitor cell function. They mediate the signaling of integrins at focal adhesions where they localize, and thus, regulate cell invasion and survival. Over-expression of these proteins is implicated in poor prognosis, increased metastasis, and resistance to chemotherapeutics in many cancers such as breast, lung, melanoma, and glioblastoma. CAS proteins have also been linked to the pathogenesis of inflammatory disorders, Alzheimer's, Parkinson's, and developmental defects. They share a common domain structure that includes an N-terminal SH3 domain, an unstructured substrate domain that contains many YxxP motifs, a serine-rich four-helix bundle, and a FAT-like C-terminal domain. Vertebrates contain four CAS proteins: BCAR1 (or p130Cas), NEDD9 (or HEF1), EFS (or SIN), and CASS4 (or HEPL). The SH3 domain of CAS proteins binds to diverse partners including FAK, FRNK, Pyk2, PTP-PEST, DOCK180, among others. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

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gi 115527076 301 LWDCHGDQPDELSFQRGDLIRILSKEYNMY-GWWVGELNSLVGIVP 345
Cdd:cd11844    5 LYDNVAESPDELAFRRGDILTVLEQNTAGLeGWWLCSLRGRQGIAP 50

Src Homology 3 (SH3) domain of Inhibitor of ASPP protein (iASPP); iASPP, also called RelA-associated inhibitor (RAI), is an oncoprotein that inhibits the apoptotic transactivation potential of p53. It is upregulated in human breast cancers expressing wild-type p53, in acute leukemias regardless of the p53 mutation status, as well as in ovarian cancer where it is associated with poor patient outcome and chemoresistance. iASPP is also a binding partner and negative regulator of p65RelA, which promotes cell proliferation and inhibits apoptosis; p65RelA has the opposite effect on cell growth compared to the p53 family. It contains a proline-rich region, four ankyrin (ANK) repeats, and an SH3 domain at its C-terminal half. The SH3 domain and the ANK repeats of iASPP contribute to the p53 binding site; they bind to the DNA binding domain of p53. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

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gi 115527076 301 LWDCHGDQPDELSFQRGDLIRILSKEYNMYGWWVGELNSLVGIVPKEYL 349
Cdd:cd11952    6 LWDYSAEFPDELSFKEGDMVTVLRKDGEGTDWWWASLCGREGYVPRNYF 54

Src homology 3 domain of Proline-Serine-Threonine Phosphatase-Interacting Protein 1; PSTPIP1, also called CD2 Binding Protein 1 (CD2BP1), is mainly expressed in hematopoietic cells. It is a binding partner of the cell surface receptor CD2 and PTP-PEST, a tyrosine phosphatase which functions in cell motility and Rac1 regulation. It also plays a role in the activation of the Wiskott-Aldrich syndrome protein (WASP), which couples actin rearrangement and T cell activation. Mutations in the gene encoding PSTPIP1 cause the autoinflammatory disorder known as PAPA (pyogenic sterile arthritis, pyoderma gangrenosum, and acne) syndrome. PSTPIP1 contains an N-terminal F-BAR domain, PEST motifs, and a C-terminal SH3 domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

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gi 115527076 298 YQGLWDCHGDQPDELSFQRGDLIRILSKEYNmyGWWVGELNSLVGIVPKEYLT 350
Cdd:cd11824    2 YSVLYDYTAQEDDELSISKGDVVAVIEKGED--GWWTVERNGQKGLVPGTYLE 52

Fifth Src homology 3 domain (or SH3E) of Intersectin-1; Intersectin-1 (ITSN1) is an adaptor protein that functions in exo- and endocytosis, actin cytoskeletal reorganization, and signal transduction. It plays a role in clathrin-coated pit (CCP) formation. It binds to many proteins through its multidomain structure and facilitate the assembly of multimeric complexes. ITSN1 localizes in membranous organelles, CCPs, the Golgi complex, and may be involved in the cell membrane trafficking system. It exists in alternatively spliced short and long isoforms. The short isoform contains two Eps15 homology domains (EH1 and EH2), a coiled-coil region and five SH3 domains (SH3A-E), while the long isoform, in addition, contains RhoGEF (also called Dbl-homologous or DH), Pleckstrin homology (PH) and C2 domains. The fifth SH3 domain (or SH3E) of ITSN1 has been shown to bind many protein partners including SGIP1, Sos1, dynamin1/2, CIN85, c-Cbl, SHIP2, N-WASP, and synaptojanin-1, among others. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

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gi 115527076 300 GLWDCHGDQPDELSFQRGDLIRILSKEYNmyGWWVGELNSLVGIVPKEYL 349
Cdd:cd11995    5 GMYDYTAQNDDELAFSKGQIINVLNKEDP--DWWKGELNGQVGLFPSNYV 52

N-terminal Src homology 3 domain of Growth factor receptor-bound protein 2 (GRB2) and related proteins; This family includes the adaptor protein GRB2 and related proteins including Drosophila melanogaster Downstream of receptor kinase (DRK), Caenorhabditis elegans Sex muscle abnormal protein 5 (Sem-5), GRB2-related adaptor protein (GRAP), GRAP2, and similar proteins. Family members contain an N-terminal SH3 domain, a central SH2 domain, and a C-terminal SH3 domain. GRB2/Sem-5/DRK is a critical signaling molecule that regulates the Ras pathway by linking tyrosine kinases to the Ras guanine nucleotide releasing protein Sos (son of sevenless), which converts Ras to the active GTP-bound state. GRAP2 plays an important role in T cell receptor (TCR) signaling by promoting the formation of the SLP-76:LAT complex, which couples the TCR to the Ras pathway. GRAP acts as a negative regulator of T cell receptor (TCR)-induced lymphocyte proliferation by downregulating the signaling to the Ras/ERK pathway. The N-terminal SH3 domain of GRB2 binds to Sos and Sos-derived proline-rich peptides. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

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gi 115527076 300 GLWDCHGDQPDELSFQRGDLIRILSKEYNMyGWWVGELNSLVGIVPKEYL 349
Cdd:cd11804    4 AKHDFKATAEDELSFKKGSILKVLNMEDDP-NWYKAELDGKEGLIPKNYI 52

Fifth Src homology 3 domain (or SH3E) of Intersectin-2; Intersectin-2 (ITSN2) is an adaptor protein that functions in exo- and endocytosis, actin cytoskeletal reorganization, and signal transduction. It plays a role in clathrin-coated pit (CCP) formation. It binds to many proteins through its multidomain structure and facilitate the assembly of multimeric complexes. ITSN2 also functions as a specific GEF for Cdc42 activation in epithelial morphogenesis, and is required in mitotic spindle orientation. It exists in alternatively spliced short and long isoforms. The short isoform contains two Eps15 homology domains (EH1 and EH2), a coiled-coil region and five SH3 domains (SH3A-E), while the long isoform, in addition, contains RhoGEF (also called Dbl-homologous or DH), Pleckstrin homology (PH) and C2 domains. The fifth SH3 domain (or SH3E) of ITSN2 is expected to bind protein partners, similar to ITSN1 which has been shown to bind many protein partners including SGIP1, Sos1, dynamin1/2, CIN85, c-Cbl, SHIP2, N-WASP, and synaptojanin-1, among others. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

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gi 115527076 301 LWDCHGDQPDELSFQRGDLIRILSKEYNmyGWWVGELNSLVGIVPKEYL 349
Cdd:cd11996    6 MYDYTANNEDELSFSKGQLINVLNKDDP--DWWQGEINGVTGLFPSNYV 52

Third Src Homology 3 domain of Nck1 adaptor protein; Nck1 (also called Nckalpha) plays a crucial role in connecting signaling pathways of tyrosine kinase receptors and important effectors in actin dynamics and cytoskeletal remodeling. It binds and activates RasGAP, resulting in the downregulation of Ras. It is also involved in the signaling of endothilin-mediated inhibition of cell migration. Nck adaptor proteins regulate actin cytoskeleton dynamics by linking proline-rich effector molecules to protein tyrosine kinases and phosphorylated signaling intermediates. They contain three SH3 domains and a C-terminal SH2 domain. They function downstream of the PDGFbeta receptor and are involved in Rho GTPase signaling and actin dynamics. Vertebrates contain two Nck adaptor proteins: Nck1 (also called Nckalpha) and Nck2, which show partly overlapping functions but also bind distinct targets. The third SH3 domain of Nck appears to prefer ligands with a PxAPxR motif. SH3 domains are protein interaction domains that usually bind to proline-rich ligands with moderate affinity and selectivity, preferentially a PxxP motif. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

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gi 115527076 299 QGLWDCHGDQPDELSFQRGDLIRILSKEYNMYGWW-VGELNSLVGIVPKEYLT 350
Cdd:cd11904    4 QALYPFSSSNDEELNFEKGEVMDVIEKPENDPEWWkCRKANGQVGLVPKNYVT 56