Ephexin Pleckstrin homology (PH) domain; Ephexin-1 (also called NGEF/ neuronal guanine nucleotide exchange factor) plays a role in the homeostatic modulation of presynaptic neurotransmitter release. Specific functions are still unknown for Ephexin-2 (also called RhoGEF19) and Ephexin-3 (also called Rho guanine nucleotide exchange factor 5/RhoGEF5, Transforming immortalized mammary oncogene/p60 TIM, and NGEF/neuronalGEF). Ephexin-4 (also called RhoGEF16) acts downstream of EphA2 to promote ligand-independent breast cancer cell migration and invasion toward epidermal growth factor through activation of RhoG. This in turn results in the activation of RhoG which recruits ELMO2 and Dock4 to form a complex with EphA2 at the tips of cortactin-rich protrusions in migrating breast cancer cells. Ephexin-5 is the specific GEF for RhoA activation and the regulation of vascular smooth muscle contractility. It interacts with EPHA4 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. The members of the Ephexin family contains a RhoGEF (DH) followed by a PH domain and an SH3 domain. The ephexin PH domain is believed to act with the DH domain in mediating protein-protein interactions. 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 1370452819 201 KVKSLPLISASRWLLKRGELFLVEETG---LFRKIASRPTCYLFLFNDVLVVTKKKSEESYMVQDYAQMNHIQVEKIEPS 277
Cdd:cd01221     1 KIKAFPLISSSRWLVKRGELTELVEDGgslTFRKKFSKTPVYLFLFNDLLLITKKKSEERYLVLDYAPRNLVQVEEVEDP 80

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|....*..
gi 1370452819 278 ELPLPGGGnrsssvPHPFQVTLLRNSEGRQEQLLLSSDSASDRARWIVALTHSERQW 334
Cdd:cd01221    81 LQLPQPLG------KNLFLLTLLENHEGKTVELLLSAESESDRERWLSALSPPKSEL 131

Src homology 3 domain of the Rho guanine nucleotide exchange factors ARHGEF16 and ARHGEF26; ARHGEF16, also called ephexin-4, acts as a GEF for RhoG, activating it by exchanging bound GDP for free GTP. RhoG is a small GTPase that is a crucial regulator of Rac in migrating cells. ARHGEF16 interacts directly with the ephrin receptor EphA2 and mediates cell migration and invasion in breast cancer cells by activating RhoG. ARHGEF26, also called SGEF (SH3 domain-containing guanine exchange factor), also activates RhoG. It is highly expressed in liver and may play a role in regulating membrane dynamics. ARHGEF16 and ARHGEF26 contain RhoGEF (also called Dbl-homologous or DH), Pleckstrin Homology (PH), and SH3 domains. The SH3 domains of ARHGEFs play an autoinhibitory role through intramolecular interactions with a proline-rich region N-terminal to the DH 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.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*
gi 1370452819 345 QVEITKAFFAKQADEVTLQQADVVLVLQQE-DGWLYGERLRDGETGWFPEDFARF 398
Cdd:cd11938     1 QVEIIKAYTAKQPDELSLQQADVVLVLQTEsDGWYYGERLRDGERGWFPSSCAKE 55

Ephexin Pleckstrin homology (PH) domain; Ephexin-1 (also called NGEF/ neuronal guanine nucleotide exchange factor) plays a role in the homeostatic modulation of presynaptic neurotransmitter release. Specific functions are still unknown for Ephexin-2 (also called RhoGEF19) and Ephexin-3 (also called Rho guanine nucleotide exchange factor 5/RhoGEF5, Transforming immortalized mammary oncogene/p60 TIM, and NGEF/neuronalGEF). Ephexin-4 (also called RhoGEF16) acts downstream of EphA2 to promote ligand-independent breast cancer cell migration and invasion toward epidermal growth factor through activation of RhoG. This in turn results in the activation of RhoG which recruits ELMO2 and Dock4 to form a complex with EphA2 at the tips of cortactin-rich protrusions in migrating breast cancer cells. Ephexin-5 is the specific GEF for RhoA activation and the regulation of vascular smooth muscle contractility. It interacts with EPHA4 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. The members of the Ephexin family contains a RhoGEF (DH) followed by a PH domain and an SH3 domain. The ephexin PH domain is believed to act with the DH domain in mediating protein-protein interactions. 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 1370452819 201 KVKSLPLISASRWLLKRGELFLVEETG---LFRKIASRPTCYLFLFNDVLVVTKKKSEESYMVQDYAQMNHIQVEKIEPS 277
Cdd:cd01221     1 KIKAFPLISSSRWLVKRGELTELVEDGgslTFRKKFSKTPVYLFLFNDLLLITKKKSEERYLVLDYAPRNLVQVEEVEDP 80

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|....*..
gi 1370452819 278 ELPLPGGGnrsssvPHPFQVTLLRNSEGRQEQLLLSSDSASDRARWIVALTHSERQW 334
Cdd:cd01221    81 LQLPQPLG------KNLFLLTLLENHEGKTVELLLSAESESDRERWLSALSPPKSEL 131

Guanine nucleotide exchange factor for Rho/Rac/Cdc42-like GTPases; Guanine nucleotide exchange factor for Rho/Rac/Cdc42-like GTPases Also called Dbl-homologous (DH) domain. It appears that PH domains invariably occur C-terminal to RhoGEF/DH domains. Improved coverage.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1370452819    1 MFEILTSEFSYQHSLSILVEEFLQS-KELRATVTQMEHHHLFSNILDVLGASQRFFEDLEQRHK-AQVLVEDISDILEEH 78
Cdd:smart00325   2 LKELLQTERNYVRDLKLLVEVFLKPlKKELKLLSPNELETLFGNIEEIYEFHRDFLDELEERIEeWDDSVERIGDVFLKL 81

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1370452819   79 AEkHFHPYIAYCSNEVYQQRTLQKLiSSNAAFREALREIERRPACGGLPMLSFLILPMQRVTRLPLLMDTLCLKTQGHSE 158
Cdd:smart00325  82 EE-FFKIYSEYCSNHPDALELLKKL-KKNPRFQKFLKEIESSPQCRRLTLESLLLKPVQRLTKYPLLLKELLKHTPEDHE 159

                          170       180
                   ....*....|....*....|.
gi 1370452819  159 RYKAASRALKAISKLVRQCNE 179
Cdd:smart00325 160 DREDLKKALKAIKELANQVNE 180

Src homology 3 domain of the Rho guanine nucleotide exchange factors ARHGEF16 and ARHGEF26; ARHGEF16, also called ephexin-4, acts as a GEF for RhoG, activating it by exchanging bound GDP for free GTP. RhoG is a small GTPase that is a crucial regulator of Rac in migrating cells. ARHGEF16 interacts directly with the ephrin receptor EphA2 and mediates cell migration and invasion in breast cancer cells by activating RhoG. ARHGEF26, also called SGEF (SH3 domain-containing guanine exchange factor), also activates RhoG. It is highly expressed in liver and may play a role in regulating membrane dynamics. ARHGEF16 and ARHGEF26 contain RhoGEF (also called Dbl-homologous or DH), Pleckstrin Homology (PH), and SH3 domains. The SH3 domains of ARHGEFs play an autoinhibitory role through intramolecular interactions with a proline-rich region N-terminal to the DH 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.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*
gi 1370452819 345 QVEITKAFFAKQADEVTLQQADVVLVLQQE-DGWLYGERLRDGETGWFPEDFARF 398
Cdd:cd11938     1 QVEIIKAYTAKQPDELSLQQADVVLVLQTEsDGWYYGERLRDGERGWFPSSCAKE 55

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 1370452819  342 DLPQVEITKAFFAKQADEVTLQQADVVLVLQQ-EDGWLYGeRLRDGETGWFPEDF 395
Cdd:smart00326   1 EGPQVRALYDYTAQDPDELSFKKGDIITVLEKsDDGWWKG-RLGRGKEGLFPSNY 54

SH3 domain; SH3 (Src homology 3) domains are often indicative of a protein involved in signal transduction related to cytoskeletal organization. First described in the Src cytoplasmic tyrosine kinase. The structure is a partly opened beta barrel.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|...
gi 1370452819 351 AFFAKQADEVTLQQADVVLVLQ-QEDGWLYGeRLRDGETGWFP 392
Cdd:pfam00018   5 DYTAQEPDELSFKKGDIIIVLEkSEDGWWKG-RNKGGKEGLIP 46

Ephexin Pleckstrin homology (PH) domain; Ephexin-1 (also called NGEF/ neuronal guanine nucleotide exchange factor) plays a role in the homeostatic modulation of presynaptic neurotransmitter release. Specific functions are still unknown for Ephexin-2 (also called RhoGEF19) and Ephexin-3 (also called Rho guanine nucleotide exchange factor 5/RhoGEF5, Transforming immortalized mammary oncogene/p60 TIM, and NGEF/neuronalGEF). Ephexin-4 (also called RhoGEF16) acts downstream of EphA2 to promote ligand-independent breast cancer cell migration and invasion toward epidermal growth factor through activation of RhoG. This in turn results in the activation of RhoG which recruits ELMO2 and Dock4 to form a complex with EphA2 at the tips of cortactin-rich protrusions in migrating breast cancer cells. Ephexin-5 is the specific GEF for RhoA activation and the regulation of vascular smooth muscle contractility. It interacts with EPHA4 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. The members of the Ephexin family contains a RhoGEF (DH) followed by a PH domain and an SH3 domain. The ephexin PH domain is believed to act with the DH domain in mediating protein-protein interactions. 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 1370452819 201 KVKSLPLISASRWLLKRGELFLVEETG---LFRKIASRPTCYLFLFNDVLVVTKKKSEESYMVQDYAQMNHIQVEKIEPS 277
Cdd:cd01221     1 KIKAFPLISSSRWLVKRGELTELVEDGgslTFRKKFSKTPVYLFLFNDLLLITKKKSEERYLVLDYAPRNLVQVEEVEDP 80

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|....*..
gi 1370452819 278 ELPLPGGGnrsssvPHPFQVTLLRNSEGRQEQLLLSSDSASDRARWIVALTHSERQW 334
Cdd:cd01221    81 LQLPQPLG------KNLFLLTLLENHEGKTVELLLSAESESDRERWLSALSPPKSEL 131

Guanine nucleotide exchange factor for Rho/Rac/Cdc42-like GTPases; Guanine nucleotide exchange factor for Rho/Rac/Cdc42-like GTPases Also called Dbl-homologous (DH) domain. It appears that PH domains invariably occur C-terminal to RhoGEF/DH domains. Improved coverage.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1370452819    1 MFEILTSEFSYQHSLSILVEEFLQS-KELRATVTQMEHHHLFSNILDVLGASQRFFEDLEQRHK-AQVLVEDISDILEEH 78
Cdd:smart00325   2 LKELLQTERNYVRDLKLLVEVFLKPlKKELKLLSPNELETLFGNIEEIYEFHRDFLDELEERIEeWDDSVERIGDVFLKL 81

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1370452819   79 AEkHFHPYIAYCSNEVYQQRTLQKLiSSNAAFREALREIERRPACGGLPMLSFLILPMQRVTRLPLLMDTLCLKTQGHSE 158
Cdd:smart00325  82 EE-FFKIYSEYCSNHPDALELLKKL-KKNPRFQKFLKEIESSPQCRRLTLESLLLKPVQRLTKYPLLLKELLKHTPEDHE 159

                          170       180
                   ....*....|....*....|.
gi 1370452819  159 RYKAASRALKAISKLVRQCNE 179
Cdd:smart00325 160 DREDLKKALKAIKELANQVNE 180

Src homology 3 domain of the Rho guanine nucleotide exchange factors ARHGEF16 and ARHGEF26; ARHGEF16, also called ephexin-4, acts as a GEF for RhoG, activating it by exchanging bound GDP for free GTP. RhoG is a small GTPase that is a crucial regulator of Rac in migrating cells. ARHGEF16 interacts directly with the ephrin receptor EphA2 and mediates cell migration and invasion in breast cancer cells by activating RhoG. ARHGEF26, also called SGEF (SH3 domain-containing guanine exchange factor), also activates RhoG. It is highly expressed in liver and may play a role in regulating membrane dynamics. ARHGEF16 and ARHGEF26 contain RhoGEF (also called Dbl-homologous or DH), Pleckstrin Homology (PH), and SH3 domains. The SH3 domains of ARHGEFs play an autoinhibitory role through intramolecular interactions with a proline-rich region N-terminal to the DH 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.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*
gi 1370452819 345 QVEITKAFFAKQADEVTLQQADVVLVLQQE-DGWLYGERLRDGETGWFPEDFARF 398
Cdd:cd11938     1 QVEIIKAYTAKQPDELSLQQADVVLVLQTEsDGWYYGERLRDGERGWFPSSCAKE 55

Src homology 3 domain of the Rho guanine nucleotide exchange factor, ephexin-1 (also called NGEF or ARHGEF27); Ephexin-1, also called NGEF (neuronal GEF) or ARHGEF27, activates RhoA, Tac1, and Cdc42 by exchanging bound GDP for free GTP. It is expressed mainly in the brain in a region associated with movement control. It regulates the stability of postsynaptic acetylcholine receptor (AChR) clusters and thus, plays a critical role in the maturation and neurotransmission of neuromuscular junctions. Ephexin-1 directly interacts with the ephrin receptor EphA4 and their coexpression enhances the ability of ephexin-1 to activate RhoA. It is required for normal axon growth and EphA-induced growth cone collapse. Ephexin-1 contains RhoGEF (also called Dbl-homologous or DH), Pleckstrin Homology (PH), and SH3 domains. The SH3 domains of ARHGEFs play an autoinhibitory role through intramolecular interactions with a proline-rich region N-terminal to the DH 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.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*....
gi 1370452819 345 QVEITKAFFAKQADEVTLQQADVVLVLQQ-EDGWLYGERLRDGETGWFP 392
Cdd:cd11939     1 QVQCVHPYVSQEPDELSLELADVLNILDKtDDGWIFGERLHDQERGWFP 49

RhoGEF, Guanine nucleotide exchange factor for Rho/Rac/Cdc42-like GTPases [Signal transduction mechanisms];

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1370452819    1 MFEILTSEFSYQHSLSILVEEFLQ----SKELRATVTQMEHHHLFSNILDVLGASQRFFEDLEQRHKAQVLVEDISDILE 76
Cdd:COG5422    489 IYEVIYTERDFVKDLEYLRDTWIKpleeSNIIPENARRNFIKHVFANINEIYAVNSKLLKALTNRQCLSPIVNGIADIFL 568

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1370452819   77 EHAEKhFHPYIAYCSNEVYQQRTLQKLISSNAAFREALREIERRPACGGLPMLSFLILPMQRVTRLPLLMDTLCLKTQGH 156
Cdd:COG5422    569 DYVPK-FEPFIKYGASQPYAKYEFEREKSVNPNFARFDHEVERLDESRKLELDGYLTKPTTRLARYPLLLEEVLKFTDPD 647

                          170       180       190       200       210       220       230       240
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1370452819  157 SERYKAASRALKAISKLVRQCNEGAHRMERMEQMYTLHTQLDFS-KVKSLPLISASRWLLKRGELFLVEEtgLFRKIASR 235
Cdd:COG5422    648 NPDTEDIPKVIDMLREFLSRLNFESGKAENRGDLFHLNQQLLFKpEYVNLGLNDEYRKIIFKGVLKRKAK--SKTDGSLR 725

                          250       260       270       280
                   ....*....|....*....|....*....|....*....|....*..
gi 1370452819  236 PTCYLFLFNDVLVVTKKKSeesymvqdyaqMNHIQVEKIEPSELPLP 282
Cdd:COG5422    726 GDIQFFLLDNMLLFCKAKA-----------VNKWRQHKVFQRPIPLE 761

Src Homology 3 domain of Amphiphysin and related domains; Amphiphysins function primarily in endocytosis and other membrane remodeling events. They exist in several isoforms and mammals possess two amphiphysin proteins from distinct genes. Amphiphysin I proteins, enriched in the brain and nervous system, contain domains that bind clathrin, Adaptor Protein complex 2 (AP2), dynamin, and synaptojanin. They function in synaptic vesicle endocytosis. Human autoantibodies to amphiphysin I hinder GABAergic signaling and contribute to the pathogenesis of paraneoplastic stiff-person syndrome. Some amphiphysin II isoforms, also called Bridging integrator 1 (Bin1), are localized in many different tissues and may function in intracellular vesicle trafficking. In skeletal muscle, Bin1 plays a role in the organization and maintenance of the T-tubule network. Mutations in Bin1 are associated with autosomal recessive centronuclear myopathy. Amphiphysins contain an N-terminal BAR domain with an additional N-terminal amphipathic helix (an N-BAR), a variable central domain, and a C-terminal SH3 domain. The SH3 domain of amphiphysins bind proline-rich motifs present in binding partners such as dynamin, synaptojanin, and nsP3. It also belongs to a subset of SH3 domains that bind ubiquitin in a site that overlaps with the peptide binding site. 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        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 1370452819 343 LPQVEITKAFFAKQADEVTLQQADVVLVL------QQEDGWLYGERLRDGETGWFPEDFARFI 399
Cdd:cd11790     2 LYKVRATHDYTAEDTDELTFEKGDVILVIpfddpeEQDEGWLMGVKESTGCRGVFPENFTERI 64

Src Homology 3 domain of fungal BOI-like proteins; This subfamily includes the Saccharomyces cerevisiae proteins BOI1 and BOI2, and similar proteins. They contain an N-terminal SH3 domain, a Sterile alpha motif (SAM), and a Pleckstrin homology (PH) domain at the C-terminus. BOI1 and BOI2 interact with the SH3 domain of Bem1p, a protein involved in bud formation. They promote polarized cell growth and participates in the NoCut signaling pathway, which is involved in the control of cytokinesis. SH3 domains bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs; they play a role in the regulation of enzymes by intramolecular interactions, changing the subcellular localization of signal pathway components and mediate multiprotein complex assemblies.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....
gi 1370452819 346 VEITKAFFAKQADEVTLQQADVVLVLQQE----DGWLYGERLRDGETGWFPEDF 395
Cdd:cd11886     2 LIVIHDFNARSEDELTLKPGDKIELIEDDeefgDGWYLGRNLRTGETGLFPVVF 55

Src Homology 3 domain superfamily; Src Homology 3 (SH3) domains are protein interaction domains that bind proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. Thus, they are referred to as proline-recognition domains (PRDs). SH3 domains are less selective and show more diverse specificity compared to other PRDs. They have been shown to bind peptide sequences that lack the PxxP motif; examples include the PxxDY motif of Eps8 and the RKxxYxxY sequence in SKAP55. SH3 domain containing proteins 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, among others. Many members of this superfamily are adaptor proteins that associate with a number of protein partners, facilitating complex formation and signal transduction.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*
gi 1370452819 352 FFAKQADEVTLQQADVVLVLQQ-EDGWLYGeRLRDGETGWFPEDF 395
Cdd:cd00174     8 YEAQDDDELSFKKGDIITVLEKdDDGWWEG-ELNGGREGLFPANY 51

First Src homology 3 domain (or SH3A) 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 first SH3 domain (or SH3A) of ITSN1 has been shown to bind many proteins including Sos1, dynamin1/2, CIN85, c-Cbl, PI3K-C2, SHIP2, N-WASP, and CdGAP, 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 1370452819 352 FFAKQADEVTLQQADVVLVLQQ---EDGWLYGErlRDGETGWFPEDFA 396
Cdd:cd11987     8 FEARSHDEITIQPGDIVMVDESqtgEPGWLGGE--LKGKTGWFPANYA 53

C-terminal Src Homology 3 domain of LIM and SH3 domain protein 1; Lasp1 is a cytoplasmic protein that binds focal adhesion proteins and is involved in cell signaling, migration, and proliferation. It is overexpressed in several cancer cells including breast, ovarian, bladder, and liver. In cancer cells, it can be found in the nucleus; its degree of nuclear localization correlates with tumor size and poor prognosis. Lasp1 is a 36kD protein containing an N-terminal LIM domain, two nebulin repeats, 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.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*....
gi 1370452819 352 FFAKQADEVTLQQADVVLVLQQ-EDGWLYGERLRDGETGWFPEDFARFI 399
Cdd:cd11934    11 YNAADEDEVSFQDGDTIVNVQQiDDGWMYGTVERTGDTGMLPANYVEAI 59

Variant SH3 domain;

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*....
gi 1370452819 350 KAFFAKQADEVTLQQADVVLVLQQ-EDGWLYGErlRDGETGWFPEDFAR 397
Cdd:pfam14604   3 YPYEPKDDDELSLQRGDVITVIEEsEDGWWEGI--NTGRTGLVPANYVE 49

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 1370452819  214 LLKRGELFLVEETGLFRKIasrpTCYLFLFNDVLVVTK-KKSEESYMVQDYAQMNHIQVEKIEPSElplpgggnrSSSVP 292
Cdd:smart00233   1 VIKEGWLYKKSGGGKKSWK----KRYFVLFNSTLLYYKsKKDKKSYKPKGSIDLSGCTVREAPDPD---------SSKKP 67

                           90       100       110
                   ....*....|....*....|....*....|....*
gi 1370452819  293 HPFQVTLlrnseGRQEQLLLSSDSASDRARWIVAL 327
Cdd:smart00233  68 HCFEIKT-----SDRKTLLLQAESEEEREKWVEAL 97

Src homology 3 domain of Nitric Oxide Synthase TRaffic INducer; Nostrin is expressed in endothelial and epithelial cells and is involved in the regulation, trafficking and targeting of endothelial NOS (eNOS). It facilitates the endocytosis of eNOS by coordinating the functions of dynamin and the Wiskott-Aldrich syndrome protein (WASP). Increased expression of Nostrin may be correlated to preeclampsia. Nostrin contains an N-terminal F-BAR domain 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.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|...
gi 1370452819 351 AFFAKQADEVTLQQADVVLVL-QQEDGWLYGErLRdGETGWFP 392
Cdd:cd11823     7 SYTANREDELSLQPGDIIEVHeKQDDGWWLGE-LN-GKKGIFP 47

Src Homology 3 domain of Amphiphysin I; Amphiphysins function primarily in endocytosis and other membrane remodeling events. They exist in several isoforms and mammals possess two amphiphysin proteins from distinct genes. Amphiphysin I proteins, enriched in the brain and nervous system, contain domains that bind clathrin, Adaptor Protein complex 2 (AP2), dynamin, and synaptojanin. They function in synaptic vesicle endocytosis. Human autoantibodies to amphiphysin I hinder GABAergic signaling and contribute to the pathogenesis of paraneoplastic stiff-person syndrome. Amphiphysins contain an N-terminal BAR domain with an additional N-terminal amphipathic helix (an N-BAR), a variable central domain, and a C-terminal SH3 domain. The SH3 domain of amphiphysins bind proline-rich motifs present in binding partners such as dynamin, synaptojanin, and nsP3. It also belongs to a subset of SH3 domains that bind ubiquitin in a site that overlaps with the peptide binding site. 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        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 1370452819 343 LPQVEITKAFFAKQADEVTLQQADVVLVL------QQEDGWLYGER------LRDGET--GWFPEDFAR 397
Cdd:cd12140     2 LYKVETLHDFEAANSDELELKRGDIVLVVpsetaaDQDAGWLTGVKesdwlqYRDASAykGLFPENFTR 70

C-terminal Src Homology 3 domain of Nebulette and LIM-nebulette (or Lasp2); Nebulette is a cardiac-specific protein that localizes to the Z-disc. It interacts with tropomyosin and is important in stabilizing actin thin filaments in cardiac muscles. Polymorphisms in the nebulette gene are associated with dilated cardiomyopathy, with some mutations resulting in severe heart failure. Nebulette is a 107kD protein that contains an N-terminal acidic region, multiple nebulin repeats, and a C-terminal SH3 domain. LIM-nebulette, also called Lasp2 (LIM and SH3 domain protein 2), is an alternatively spliced variant of nebulette. Although it shares a gene with nebulette, Lasp2 is not transcribed from a muscle-specific promoter, giving rise to its multiple tissue expression pattern with highest amounts in the brain. It can crosslink actin filaments and it affects cell spreading. Lasp2 is a 34kD protein containing an N-terminal LIM domain, three nebulin repeats, 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.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*....
gi 1370452819 352 FFAKQADEVTLQQADVVLVLQQ-EDGWLYGERLRDGETGWFPEDFARFI 399
Cdd:cd11935     9 YSAQDEDEVSFRDGDYIVNVQPiDEGWMYGTVQRTGRTGMLPANYIEFV 57

Second Src homology 3 domain (or SH3B) 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 second SH3 domain (or SH3B) of ITSN1 has been shown to bind WNK and CdGAP. 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 1370452819 354 AKQADEVTLQQADVVLVLQQEDGWLYGErlRDGETGWFPEDFARF 398
Cdd:cd11989    10 AKKDNHLNFNKNDVITVLEQQDMWWFGE--VQGQKGWFPKSYVKL 52

Src Homology 3 domain of Pak Interactive eXchange factors; PIX proteins are Rho guanine nucleotide exchange factors (GEFs), which activate small GTPases by exchanging bound GDP for free GTP. They act as GEFs for both Cdc42 and Rac 1, and have been implicated in cell motility, adhesion, neurite outgrowth, and cell polarity. Vertebrates contain two proteins from the PIX subfamily, alpha-PIX and beta-PIX. Alpha-PIX, also called ARHGEF6, is localized in dendritic spines where it regulates spine morphogenesis. Mutations in the ARHGEF6 gene cause X-linked intellectual disability in humans. Beta-PIX play roles in regulating neuroendocrine exocytosis, focal adhesion maturation, cell migration, synaptic vesicle localization, and insulin secretion. PIX proteins contain an N-terminal SH3 domain followed by RhoGEF (also called Dbl-homologous or DH) and Pleckstrin Homology (PH) domains, and a C-terminal leucine-zipper domain for dimerization. The SH3 domain of PIX binds to an atypical PxxxPR motif in p21-activated kinases (PAKs) with high affinity. The binding of PAKs to PIX facilitate the localization of PAKs to focal complexes and also localizes PAKs to PIX targets Cdc43 and Rac, leading to the activation of PAKs. 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 1370452819 351 AFFAKQADEVTLQQADVVLVLQQEDG--WlygERLRDGETGWFPEDFAR 397
Cdd:cd11877     7 NFEGTNEDELSFDKGDIITVTQVVEGgwW---EGTLNGKTGWFPSNYVK 52

C-terminal Src Homology 3 domain of the Nebulin family of proteins; Nebulin family proteins contain multiple nebulin repeats, and may contain an N-terminal LIM domain and/or a C-terminal SH3 domain. They have molecular weights ranging from 34 to 900 kD, depending on the number of nebulin repeats, and they all bind actin. They are involved in the regulation of actin filament architecture and function as stabilizers and scaffolds for cytoskeletal structures with which they associate, such as long actin filaments or focal adhesions. Nebulin family proteins that contain a C-terminal SH3 domain include the giant filamentous protein nebulin, nebulette, Lasp1, and Lasp2. Lasp2, also called LIM-nebulette, is an alternatively spliced variant of nebulette. 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 1370452819 354 AKQADEVTLQQADVVLVLQQ-EDGWLYGERLRDGETGWFP 392
Cdd:cd11789    10 AADDDEVSFQEGDVIINVEIiDDGWMEGTVQRTGQSGMLP 49

First Src homology 3 domain (or SH3A) 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 first SH3 domain (or SH3A) of ITSN2 is expected to bind many protein partners, similar to ITSN1 which has been shown to bind Sos1, dynamin1/2, CIN85, c-Cbl, PI3K-C2, SHIP2, N-WASP, and CdGAP, 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 1370452819 352 FFAKQADEVTLQQADVVLVLQQ---EDGWLYGERlrDGETGWFPEDFA 396
Cdd:cd11988    10 FEARNHDEMSFNAGDIIQVDEKtvgEPGWLYGSF--QGNFGWFPCNYV 55

Src Homology 3 domain of fungal peroxisomal membrane protein Pex13p; Pex13p, located in the peroxisomal membrane, contains two transmembrane regions and a C-terminal SH3 domain. It binds to the peroxisomal targeting type I (PTS1) receptor Pex5p and the docking factor Pex14p through its SH3 domain. It is essential for both PTS1 and PTS2 protein import pathways into the peroxisomal matrix. Pex13p binds Pex14p, which contains a PxxP motif, in a classical fashion to the proline-rich ligand binding site of its SH3 domain. It binds the WxxxF/Y motif of Pex5p in a novel site that does not compete with Pex14p binding. 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 1370452819 359 EVTLQQADVVLVLQQED------GWLYGeRLRDGETGWFPEDF 395
Cdd:cd11771    16 ELSLKKGDIVAVLSKTDplgrdsEWWKG-RTRDGRIGWFPSNY 57

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 1370452819 354 AKQADEVTLQQADVVLVLQQE---DGWLYGErlRDGETGWFPEDFA 396
Cdd:cd11875    10 AENEDELTLREGDIVTILSKDcedKGWWKGE--LNGKRGVFPDNFV 53

FYVE, RhoGEF and PH domain containing/faciogenital dysplasia family proteins, N-terminal Pleckstrin homology (PH) domain; In general, FGDs have a RhoGEF (DH) domain, followed by an N-terminal PH domain, a FYVE domain and a C-terminal PH domain. All FGDs are guanine nucleotide exchange factors that activates the Rho GTPase Cdc42, an important regulator of membrane trafficking. The RhoGEF domain is responsible for GEF catalytic activity, while the N-terminal PH domain is involved in intracellular targeting of the DH domain. Mutations in the FGD1 gene are responsible for the X-linked disorder known as faciogenital dysplasia (FGDY). 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 1370452819 228 LFRKIASRPTCYLFLFNDVLVVTKKKseESYMVQDYAQMNHIQVEKIEPSELPLPgggnrssSVPHPFQVtllrnsEGRQ 307
Cdd:cd13328     8 LSAKNGTPQPRYLFLFNDMLLYCVPK--LSLVGQKFSVRNRLDVAGMKVREPVNE-------NYPHTFKI------SGKE 72

                          90       100
                  ....*....|....*....|
gi 1370452819 308 EQLLLSSDSASDRARWIVAL 327
Cdd:cd13328    73 RSLELQASSAEEKDEWIQAI 92

First Src Homology 3 domain (SH3A) of Cbl-interacting protein of 85 kDa; CIN85, also called SH3 domain-containing kinase-binding protein 1 (SH3KBP1) or CD2-binding protein 3 (CD2BP3) or Ruk, is an adaptor protein that is involved in the downregulation of receptor tyrosine kinases by facilitating endocytosis through interaction with endophilin-associated ubiquitin ligase Cbl proteins. It is also important in many other cellular processes including vesicle-mediated transport, cytoskeletal remodelling, apoptosis, cell adhesion and migration, and viral infection, among others. CIN85 exists as multiple variants from alternative splicing; the main variant contains three SH3 domains, a proline-rich region, and a C-terminal coiled-coil domain. All of these domains enable CIN85 to bind various protein partners and assemble complexes that have been implicated in many different functions. This alignment model represents the first SH3 domain (SH3A) of CIN85; SH3A binds to internal proline-rich motifs within the proline-rich region. This intramolecular interaction serves as a regulatory mechanism to keep CIN85 in a closed conformation, preventing the recruitment of other proteins. SH3A has also been shown to bind ubiquitin and to an atypical PXXXPR motif at the C-terminus of Cbl and the cytoplasmic end of the cell adhesion protein CD2. 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 1370452819 354 AKQADEVTLQQADVVLVLQQED-GWLYGErlRDGETGWFPEDFAR 397
Cdd:cd12052    10 AQHEDELTITVGDIITKIKKDDgGWWEGE--IKGRRGLFPDNFVR 52

Third Src Homology 3 domain of SH3 domain containing ring finger 2; SH3RF2 is also called POSHER (POSH-eliminating RING protein) or HEPP1 (heart protein phosphatase 1-binding protein). It acts as an anti-apoptotic regulator of the JNK pathway by binding to and promoting the degradation of SH3RF1 (or POSH), a scaffold protein that is required for pro-apoptotic JNK activation. It may also play a role in cardiac functions together with protein phosphatase 1. SH3RF2 contains an N-terminal RING finger domain and three SH3 domains. This model represents the third SH3 domain, located in the middle, of SH3RF2. 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 1370452819 351 AFFAKQADEVTLQQADVVLVL-QQEDGWLYGERLRDGETGWFPEDF 395
Cdd:cd11784     7 SYSAHRPEELELQKGEGVRVLgKFQEGWLRGLSLVTGRVGIFPSNY 52

Src Homology 3 domain of Class A Dedicator of Cytokinesis proteins 1 and 5; Dock1, also called Dock180, and Dock5 are class A DOCKs and are atypical guanine nucleotide exchange factors (GEFs) that lack the conventional Dbl homology (DH) domain. Dock1 interacts with the scaffold protein Elmo and the resulting complex functions upstream of Rac in many biological events including phagocytosis of apoptotic cells, cell migration and invasion. Dock5 functions upstream of Rac1 to regulate osteoclast function. All DOCKs contain two homology domains: the DHR-1 (Dock homology region-1), also called CZH1 (CED-5, Dock180, and MBC-zizimin homology 1), and DHR-2 (also called CZH2 or Docker). The DHR-1 domain binds phosphatidylinositol-3,4,5-triphosphate while DHR-2 contains the catalytic activity for Rac and/or Cdc42. Class A DOCKs also contain an SH3 domain at the N-terminal region and a PxxP motif at the C-terminus; they are specific GEFs for Rac. The SH3 domain of Dock1 binds to DHR-2 in an autoinhibitory manner; binding of Elmo to the SH3 domain of Dock1 exposes the DHR-2 domain and promotes GEF activity. 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 1370452819 354 AKQADEVTLQQADVVLVLQQEDGWLYGERLRD-GETGWFPEDF 395
Cdd:cd12051    10 ARGPDELSLQIGDTVHILETYEGWYRGYTLRKkSKKGIFPASY 52

Third Src Homology 3 domain of SH3 domain containing ring finger 3, an E3 ubiquitin-protein ligase; SH3RF3 is also called POSH2 (Plenty of SH3s 2) or SH3MD4 (SH3 multiple domains protein 4). It is a scaffold protein with E3 ubiquitin-protein ligase activity. It was identified in the screen for interacting partners of p21-activated kinase 2 (PAK2). It may play a role in regulating JNK mediated apoptosis in certain conditions. It also interacts with GTP-loaded Rac1. SH3RF3 is highly homologous to SH3RF1; it also contains an N-terminal RING finger domain and four SH3 domains. This model represents the third SH3 domain, located in the middle, of SH3RF3. 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 1370452819 351 AFFAKQADEVTLQQADVVLVLQQ-EDGWLYGERLRDGETGWFPEDF 395
Cdd:cd11925     8 AYKPQKNDELELRKGEMYRVIEKcQDGWFKGTSLRTGVSGVFPGNY 53

Src Homology 3 domain of alpha-Pak Interactive eXchange factor; Alpha-PIX, also called Rho guanine nucleotide exchange factor 6 (ARHGEF6) or Cool (Cloned out of Library)-2, activates small GTPases by exchanging bound GDP for free GTP. It acts as a GEF for both Cdc42 and Rac 1, and is localized in dendritic spines where it regulates spine morphogenesis. It controls dendritic length and spine density in the hippocampus. Mutations in the ARHGEF6 gene cause X-linked intellectual disability in humans. PIX proteins contain an N-terminal SH3 domain followed by RhoGEF (also called Dbl-homologous or DH) and Pleckstrin Homology (PH) domains, and a C-terminal leucine-zipper domain for dimerization. The SH3 domain of PIX binds to an atypical PxxxPR motif in p21-activated kinases (PAKs) with high affinity. The binding of PAKs to PIX facilitate the localization of PAKs to focal complexes and also localizes PAKs to PIX targets Cdc43 and Rac, leading to the activation of PAKs. 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 1370452819 348 ITKAFF---AKQADEVTLQQADVVLVLQQEDG-WLYGERlrDGETGWFPEDFARFITS 401
Cdd:cd12060     3 VVKARFnfkQTNEDELSVCKGDIIYVTRVEEGgWWEGTL--NGKTGWFPSNYVREIKS 58

Third Src Homology 3 domain of SH3 domain containing ring finger 1 (SH3RF1), SH3RF3, and similar domains; SH3RF1 (or POSH) and SH3RF3 (or POSH2) are scaffold proteins that function as E3 ubiquitin-protein ligases. They contain an N-terminal RING finger domain and four SH3 domains. This model represents the third SH3 domain, located in the middle of SH3RF1 and SH3RF3, and similar domains. SH3RF1 plays a role in calcium homeostasis through the control of the ubiquitin domain protein Herp. It may also have a role in regulating death receptor mediated and JNK mediated apoptosis. SH3RF3 interacts with p21-activated kinase 2 (PAK2) and GTP-loaded Rac1. It may play a role in regulating JNK mediated apoptosis in certain conditions. 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 1370452819 354 AKQADEVTLQQADVVLVLQQ-EDGWLYGERLRDGETGWFP 392
Cdd:cd11783    10 PQKPDELELRKGEMYTVTEKcQDGWFKGTSLRTGQSGVFP 49

Src homology 3 domain of JNK-interacting protein 2; JNK-interacting protein 2 (JIP2) is also called Mitogen-activated protein kinase 8-interacting protein 2 (MAPK8IP2) or Islet-brain-2 (IB2). It is widely expressed in the brain, where it forms complexes with fibroblast growth factor homologous factors (FHFs), which facilitates activation of the p38delta MAPK. JIP2 is enriched in postsynaptic densities and may play a role in motor and cognitive function. In addition to a JNK binding domain, JIP2 also contains SH3 and Phosphotyrosine-binding (PTB) domains. The SH3 domain of the related protein JIP1 homodimerizes at the interface usually involved in proline-rich ligand recognition, despite the lack of this motif in the domain itself. 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 1370452819 352 FFAKQADEVTLQQADVVLVLQQEDG-WLYGERLRDGETGWFPEDFA 396
Cdd:cd11942     8 FIPRHEDELELDVDDPLLVEAEEDDyWYRGYNMRTGERGIFPAFYA 53

Pleckstrin homology domain-containing family G member 5 and 6 pleckstrin homology (PH) domain; PLEKHG5 has a RhoGEF DH/double-homology domain in tandem with a PH domain which is involved in phospholipid binding. PLEKHG5 activates the nuclear factor kappa B (NFKB1) signaling pathway. Mutations in PLEKHG5 are associated with autosomal recessive distal spinal muscular atrophy. PLEKHG6 (also called MyoGEF) has no known function to date. 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
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1370452819 212 RWLLKRGELFLVEETGlfrkiaSRPTCYLFLFNDVLVVTK--KKSEESYMV--QDYAqmnhiqVEKIEPSELPLPGG 284
Cdd:cd13244     1 RRLLLEGDLRLKEGKG------SKVDVHCFLFTDMLLICKpvKRKKDRLKVirPPYL------VDKLVVQELKDPGG 65