P-loop containing Nucleoside Triphosphate Hydrolases; Members of the P-loop NTPase domain superfamily are characterized by a conserved nucleotide phosphate-binding motif, also referred to as the Walker A motif (GxxxxGK[S/T], where x is any residue), and the Walker B motif (hhhh[D/E], where h is a hydrophobic residue). The Walker A and B motifs bind the beta-gamma phosphate moiety of the bound nucleotide (typically ATP or GTP) and the Mg2+ cation, respectively. The P-loop NTPases are involved in diverse cellular functions, and they can be divided into two major structural classes: the KG (kinase-GTPase) class which includes Ras-like GTPases and its circularly permutated YlqF-like; and the ASCE (additional strand catalytic E) class which includes ATPase Binding Cassette (ABC), DExD/H-like helicases, 4Fe-4S iron sulfur cluster binding proteins of NifH family, RecA-like F1-ATPases, and ATPases Associated with a wide variety of Activities (AAA). Also included are a diverse set of nucleotide/nucleoside kinase families.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|...
gi 1519378    1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVRTERGSDVIIMLV 53
Cdd:cd01861  59 QERFRSLIPSYIRDSSVAVVVYDITNRQSFDNTDKWIDDVRDERGNDVIIVLV 111

Rab GTPase family 6 (Rab6); Rab6 is involved in microtubule-dependent transport pathways through the Golgi and from endosomes to the Golgi. Rab6A of mammals is implicated in retrograde transport through the Golgi stack, and is also required for a slow, COPI-independent, retrograde transport pathway from the Golgi to the endoplasmic reticulum (ER). This pathway may allow Golgi residents to be recycled through the ER for scrutiny by ER quality-control systems. Yeast Ypt6p, the homolog of the mammalian Rab6 GTPase, is not essential for cell viability. Ypt6p acts in endosome-to-Golgi, in intra-Golgi retrograde transport, and possibly also in Golgi-to-ER trafficking. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins. Due to the presence of truncated sequences in this CD, the lipid modification site is not available for annotation.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|...
gi 1519378    1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVRTERGSDVIIMLV 53
Cdd:cd01861  59 QERFRSLIPSYIRDSSVAVVVYDITNRQSFDNTDKWIDDVRDERGNDVIIVLV 111

Rab subfamily of small GTPases; Rab GTPases are implicated in vesicle trafficking.

                           10        20        30        40        50
                   ....*....|....*....|....*....|....*....|....*....|...
gi 1519378       1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVRTERGSDVIIMLV 53
Cdd:smart00175  59 QERFRSITSSYYRGAVGALLVYDITNRESFENLENWLKELREYASPNVVIMLV 111

Rab GTPase family 6 (Rab6); Rab6 is involved in microtubule-dependent transport pathways through the Golgi and from endosomes to the Golgi. Rab6A of mammals is implicated in retrograde transport through the Golgi stack, and is also required for a slow, COPI-independent, retrograde transport pathway from the Golgi to the endoplasmic reticulum (ER). This pathway may allow Golgi residents to be recycled through the ER for scrutiny by ER quality-control systems. Yeast Ypt6p, the homolog of the mammalian Rab6 GTPase, is not essential for cell viability. Ypt6p acts in endosome-to-Golgi, in intra-Golgi retrograde transport, and possibly also in Golgi-to-ER trafficking. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins. Due to the presence of truncated sequences in this CD, the lipid modification site is not available for annotation.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|...
gi 1519378    1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVRTERGSDVIIMLV 53
Cdd:cd01861  59 QERFRSLIPSYIRDSSVAVVVYDITNRQSFDNTDKWIDDVRDERGNDVIIVLV 111

Rab subfamily of small GTPases; Rab GTPases are implicated in vesicle trafficking.

                           10        20        30        40        50
                   ....*....|....*....|....*....|....*....|....*....|...
gi 1519378       1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVRTERGSDVIIMLV 53
Cdd:smart00175  59 QERFRSITSSYYRGAVGALLVYDITNRESFENLENWLKELREYASPNVVIMLV 111

Rab-related GTPase family includes Rab5 and Rab22; regulates early endosome fusion; The Rab5-related subfamily includes Rab5 and Rab22 of mammals, Ypt51/Ypt52/Ypt53 of yeast, and RabF of plants. The members of this subfamily are involved in endocytosis and endocytic-sorting pathways. In mammals, Rab5 GTPases localize to early endosomes and regulate fusion of clathrin-coated vesicles to early endosomes and fusion between early endosomes. In yeast, Ypt51p family members similarly regulate membrane trafficking through prevacuolar compartments. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins. Due to the presence of truncated sequences in this CD, the lipid modification site is not available for annotation.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|...
gi 1519378    1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVRTERGSDVIIMLV 53
Cdd:cd01860  60 QERYRSLAPMYYRGAAAAIVVYDITSEESFEKAKSWVKELQEHGPPNIVIALA 112

Rab GTPase family 21 (Rab21); The localization and function of Rab21 are not clearly defined, with conflicting data reported. Rab21 has been reported to localize in the ER in human intestinal epithelial cells, with partial colocalization with alpha-glucosidase, a late endosomal/lysosomal marker. More recently, Rab21 was shown to colocalize with and affect the morphology of early endosomes. In Dictyostelium, GTP-bound Rab21, together with two novel LIM domain proteins, LimF and ChLim, has been shown to regulate phagocytosis. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins. Due to the presence of truncated sequences in this CD, the lipid modification site is not available for annotation.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|...
gi 1519378    1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVRTERGSDVIIMLV 53
Cdd:cd04123  59 QERYHALGPIYYRDADGAILVYDITDADSFQKVKKWIKELKQMRGNNISLVIV 111

Rab GTPase family 19 (Rab19); Rab19 subfamily. Rab19 proteins are associated with Golgi stacks. Similarity analysis indicated that Rab41 is closely related to Rab19. However, the function of these Rabs is not yet characterized. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins. Due to the presence of truncated sequences in this CD, the lipid modification site is not available for annotation.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|...
gi 1519378    1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVRTERGSDVIIMLV 53
Cdd:cd01864  62 QERFRTITQSYYRSANGAIIAYDITRRSSFESVPHWIEEVEKYGASNVVLLLI 114

Ras of Complex, Roc, domain of DAPkinase; Roc, or Ras of Complex, proteins are mitochondrial Rho proteins (Miro-1, and Miro-2) and atypical Rho GTPases. Full-length proteins have a unique domain organization, with tandem GTP-binding domains and two EF hand domains (pfam00036) that may bind calcium. They are also larger than classical small GTPases. It has been proposed that they are involved in mitochondrial homeostasis and apoptosis.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|
gi 1519378      1 QERFRSLIPSYIRDSTVAVVVYDITnlnSFQQTSKWIDDVRTERGSDVII 50
Cdd:pfam08477  61 QERFRSLHPFYYRGAAAALLVYDSR---TFSNLKYWLRELKKYAGNSPVI 107

Rab GTPase family 2 (Rab2); Rab2 is localized on cis-Golgi membranes and interacts with Golgi matrix proteins. Rab2 is also implicated in the maturation of vesicular tubular clusters (VTCs), which are microtubule-associated intermediates in transport between the ER and Golgi apparatus. In plants, Rab2 regulates vesicle trafficking between the ER and the Golgi bodies and is important to pollen tube growth. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins. Due to the presence of truncated sequences in this CD, the lipid modification site is not available for annotation.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|...
gi 1519378    1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVRTERGSDVIIMLV 53
Cdd:cd01866  63 QESFRSITRSYYRGAAGALLVYDITRRETFNHLTSWLEDARQHSNSNMTIMLI 115

Rab GTPase family 26 (Rab26); Rab26 subfamily. First identified in rat pancreatic acinar cells, Rab26 is believed to play a role in recruiting mature granules to the plasma membrane upon beta-adrenergic stimulation. Rab26 belongs to the Rab functional group III, which are considered key regulators of intracellular vesicle transport during exocytosis. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|...
gi 1519378    1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVRTERGSDVIIMLV 53
Cdd:cd04112  60 QERFRSVTHAYYRDAHALLLLYDVTNKSSFDNIRAWLTEILEYAQSDVVIMLL 112

Rab GTPase family 39 (Rab39); Found in eukaryotes, Rab39 is mainly found in epithelial cell lines, but is distributed widely in various human tissues and cell lines. It is believed to be a novel Rab protein involved in regulating Golgi-associated vesicular transport during cellular endocytosis. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|.
gi 1519378    1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVR 41
Cdd:cd04111  62 QERFRSITRSYYRNSVGVLLVFDITNRESFEHVHDWLEEAR 102

Rab GTPase families 8, 10, 13 (Rab8, Rab10, Rab13); Rab8/Sec4/Ypt2 are known or suspected to be involved in post-Golgi transport to the plasma membrane. It is likely that these Rabs have functions that are specific to the mammalian lineage and have no orthologs in plants. Rab8 modulates polarized membrane transport through reorganization of actin and microtubules, induces the formation of new surface extensions, and has an important role in directed membrane transport to cell surfaces. The Ypt2 gene of the fission yeast Schizosaccharomyces pombe encodes a member of the Ypt/Rab family of small GTP-binding proteins, related in sequence to Sec4p of Saccharomyces cerevisiae but closer to mammalian Rab8. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins. Due to the presence of truncated sequences in this CD, the lipid modification site is not available for annotation.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|...
gi 1519378    1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVRTERGSDVIIMLV 53
Cdd:cd01867  62 QERFRTITTSYYRGAMGIILVYDITDEKSFENIKNWMRNIDEHASEDVERMLV 114

Rab GTPase family 33 includes Rab33A and Rab33B; Rab33B/Rab33A subfamily. Rab33B is ubiquitously expressed in mouse tissues and cells, where it is localized to the medial Golgi cisternae. It colocalizes with alpha-mannose II. Together with the other cisternal Rabs, Rab6A and Rab6A', it is believed to regulate the Golgi response to stress and is likely a molecular target in stress-activated signaling pathways. Rab33A (previously known as S10) is expressed primarily in the brain and immune system cells. In humans, it is located on the X chromosome at Xq26 and its expression is down-regulated in tuberculosis patients. Experimental evidence suggests that Rab33A is a novel CD8+ T cell factor that likely plays a role in tuberculosis disease processes. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins. Due to the presence of truncated sequences in this CD, the lipid modification site is not available for annotation.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|..
gi 1519378    1 QERFR-SLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVR 41
Cdd:cd04115  61 QERFRkSMVQHYYRNVHAVVFVYDVTNMASFHSLPSWIEECE 102

Rab GTPase family 30 (Rab30); Rab30 subfamily. Rab30 appears to be associated with the Golgi stack. It is expressed in a wide variety of tissue types and in humans maps to chromosome 11. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins. Due to the presence of truncated sequences in this CD, the lipid modification site is not available for annotation.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|...
gi 1519378    1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVRTERGSDVIIMLV 53
Cdd:cd04114  66 QERFRSITQSYYRSANALILTYDITCEESFRCLPEWLREIEQYANNKVITILV 118

Rab GTPase family 12 (Rab12); Rab12 was first identified in canine cells, where it was localized to the Golgi complex. The specific function of Rab12 remains unknown, and inconsistent results about its cellular localization have been reported. More recent studies have identified Rab12 associated with post-Golgi vesicles, or with other small vesicle-like structures but not with the Golgi complex. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|...
gi 1519378    1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVRTERGSDVIIMLV 53
Cdd:cd04120  59 QERFNSITSAYYRSAKGIILVYDITKKETFDDLPKWMKMIDKYASEDAELLLV 111

Rab GTPase family 35 (Rab35); Rab35 is one of several Rab proteins to be found to participate in the regulation of osteoclast cells in rats. In addition, Rab35 has been identified as a protein that interacts with nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) in human cells. Overexpression of NPM-ALK is a key oncogenic event in some anaplastic large-cell lymphomas; since Rab35 interacts with N|PM-ALK, it may provide a target for cancer treatments. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|....*....
gi 1519378    1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVrtERGSDVI 49
Cdd:cd04110  65 QERFRTITSTYYRGTHGVIVVYDVTNGESFVNVKRWLQEI--EQNCDDV 111

Rab GTPase family 15 (Rab15); Rab15 colocalizes with the transferrin receptor in early endosome compartments, but not with late endosomal markers. It codistributes with Rab4 and Rab5 on early/sorting endosomes, and with Rab11 on pericentriolar recycling endosomes. It is believed to function as an inhibitory GTPase that regulates distinct steps in early endocytic trafficking. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins. Due to the presence of truncated sequences in this CD, the lipid modification site is not available for annotation.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|
gi 1519378    1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDV 40
Cdd:cd04117  59 QERYQTITKQYYRRAQGIFLVYDISSERSYQHIMKWVSDV 98

Rab family protein; Provisional

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*
gi 1519378     1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSK-WIDDVRT-ERGSDVIIMLV 53
Cdd:PLN03118  72 QERFRTLTSSYYRNAQGIILVYDVTRRETFTNLSDvWGKEVELySTNQDCVKMLV 126

Rab GTPase family 40 (Rab40) contains Rab40a, Rab40b and Rab40c; The Rab40 subfamily contains Rab40a, Rab40b, and Rab40c, which are all highly homologous. In rat, Rab40c is localized to the perinuclear recycling compartment (PRC), and is distributed in a tissue-specific manor, with high expression in brain, heart, kidney, and testis, low expression in lung and liver, and no expression in spleen and skeletal muscle. Rab40c is highly expressed in differentiated oligodendrocytes but minimally expressed in oligodendrocyte progenitors, suggesting a role in the vesicular transport of myelin components. Unlike most other Ras-superfamily proteins, Rab40c was shown to have a much lower affinity for GTP, and an affinity for GDP that is lower than for GTP. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|
gi 1519378    1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDV 40
Cdd:cd04121  65 QGRFCTIFRSYSRGAQGIILVYDITNRWSFDGIDRWIKEI 104

Rab GTPase-like family 2 (Rab-like2); RabL2 (Rab-like2) subfamily. RabL2s are novel Rab proteins identified recently which display features that are distinct from other Rabs, and have been termed Rab-like. RabL2 contains RabL2a and RabL2b, two very similar Rab proteins that share > 98% sequence identity in humans. RabL2b maps to the subtelomeric region of chromosome 22q13.3 and RabL2a maps to 2q13, a region that suggests it is also a subtelomeric gene. Both genes are believed to be expressed ubiquitously, suggesting that RabL2s are the first example of duplicated genes in human proximal subtelomeric regions that are both expressed actively. Like other Rab-like proteins, RabL2s lack a prenylation site at the C-terminus. The specific functions of RabL2a and RabL2b remain unknown. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|....
gi 1519378    1 QERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDDVRTER 44
Cdd:cd04124  59 QERFQTMHASYYHKAHACILVFDVTRKITYKNLSKWYEELREYR 102

Rab GTPase family 28 (Rab28); Rab28 subfamily. First identified in maize, Rab28 has been shown to be a late embryogenesis-abundant (Lea) protein that is regulated by the plant hormone abcisic acid (ABA). In Arabidopsis, Rab28 is expressed during embryo development and is generally restricted to provascular tissues in mature embryos. Unlike maize Rab28, it is not ABA-inducible. Characterization of the human Rab28 homolog revealed two isoforms, which differ by a 95-base pair insertion, producing an alternative sequence for the 30 amino acids at the C-terminus. The two human isoforms are presumably the result of alternative splicing. Since they differ at the C-terminus but not in the GTP-binding region, they are predicted to be targeted to different cellular locations. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|
gi 1519378    7 LIPSYIRDSTVAVVVYDITNLNSFQQTSKW---IDDVRTERGSDVIIMLV 53
Cdd:cd04109  66 MLDKYIYGAQAVCLVYDITNSQSFENLEDWlsvVKKVNEESETKPKMVLV 115

Rap2 family GTPase consists of Rap2a, Rap2b, and Rap2c; The Rap2 subgroup is part of the Rap subfamily of the Ras family. It consists of Rap2a, Rap2b, and Rap2c. Both isoform 3 of the human mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4) and Traf2- and Nck-interacting kinase (TNIK) are putative effectors of Rap2 in mediating the activation of c-Jun N-terminal kinase (JNK) to regulate the actin cytoskeleton. In human platelets, Rap2 was shown to interact with the cytoskeleton by binding the actin filaments. In embryonic Xenopus development, Rap2 is necessary for the Wnt/beta-catenin signaling pathway. The Rap2 interacting protein 9 (RPIP9) is highly expressed in human breast carcinomas and correlates with a poor prognosis, suggesting a role for Rap2 in breast cancer oncogenesis. Rap2b, but not Rap2a, Rap2c, Rap1a, or Rap1b, is expressed in human red blood cells, where it is believed to be involved in vesiculation. A number of additional effector proteins for Rap2 have been identified, including the RalGEFs RalGDS, RGL, and Rlf, which also interact with Rap1 and Ras. Most Ras proteins contain a lipid modification site at the C-terminus, with a typical sequence motif CaaX, where a = an aliphatic amino acid and X = any amino acid. Lipid binding is essential for membrane attachment, a key feature of most Ras proteins. Due to the presence of truncated sequences in this CD, the lipid modification site is not available for annotation.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|...
gi 1519378    2 ERFRSLIPSYIRDSTVAVVVYDITNLNSFQQTSKWIDD-VRTERGSDVIIMLV 53
Cdd:cd04176  60 EQFASMRDLYIKNGQGFIVVYSLVNQQTFQDIKPMRDQiVRVKGYEKVPIILV 112