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        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   1 MREQYMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRDEFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEAS 80
Cdd:cd04145   66 MREQYMRTGEGFLLVFSVTDRGSFEEVDKFHTQILRVKDRDEFPMILVGNKADLEHQRQVSREEGQELARQLKIPYIETS 145

                         90
                 ....*....|....*....
gi 293597521  81 AKIRMNVDQAFHELVRVIR 99
Cdd:cd04145  146 AKDRVNVDKAFHDLVRVIR 164

R-Ras2/TC21, M-Ras/R-Ras3; The M-Ras/R-Ras-like subfamily contains R-Ras2/TC21, M-Ras/R-Ras3, and related members of the Ras family. M-Ras is expressed in lympho-hematopoetic cells. It interacts with some of the known Ras effectors, but appears to also have its own effectors. Expression of mutated M-Ras leads to transformation of several types of cell lines, including hematopoietic cells, mammary epithelial cells, and fibroblasts. Overexpression of M-Ras is observed in carcinomas from breast, uterus, thyroid, stomach, colon, kidney, lung, and rectum. In addition, expression of a constitutively active M-Ras mutant in murine bone marrow induces a malignant mast cell leukemia that is distinct from the monocytic leukemia induced by H-Ras. TC21, along with H-Ras, has been shown to regulate the branching morphogenesis of ureteric bud cell branching in mice. 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        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   1 MREQYMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRDEFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEAS 80
Cdd:cd04145   66 MREQYMRTGEGFLLVFSVTDRGSFEEVDKFHTQILRVKDRDEFPMILVGNKADLEHQRQVSREEGQELARQLKIPYIETS 145

                         90
                 ....*....|....*....
gi 293597521  81 AKIRMNVDQAFHELVRVIR 99
Cdd:cd04145  146 AKDRVNVDKAFHDLVRVIR 164

Ras-like protein; Provisional

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   1 MREQYMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRDEFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEAS 80
Cdd:PTZ00369  69 MRDQYMRTGQGFLCVYSITSRSSFEEIASFREQILRVKDKDRVPMILVGNKCDLDSERQVSTGEGQELAKSFGIPFLETS 148

                         90       100       110       120
                 ....*....|....*....|....*....|....*....|....*..
gi 293597521  81 AKIRMNVDQAFHELVRVIRKFQEQECPPspeptrKEKDKKGCHCVIF 127
Cdd:PTZ00369 149 AKQRVNVDEAFYELVREIRKYLKEDMPS------QKQKKKGGLCLIL 189

GTPase SAR1 family domain [General function prediction only];

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   2 REQYMRTGEG---FLLVFSVTDRGSFEEIYKFQRQILRVKDRdeFPMILIGNKADLDHQRQVTQEEGQQLARQLK--VTY 76
Cdd:COG1100   70 RQFYARQLTGaslYLFVVDGTREETLQSLYELLESLRRLGKK--SPIILVLNKIDLYDEEEIEDEERLKEALSEDniVEV 147

                         90       100
                 ....*....|....*....|...
gi 293597521  77 MEASAKIRMNVDQAFHELVRVIR 99
Cdd:COG1100  148 VATSAKTGEGVEELFAALAEILR 170

R-Ras2/TC21, M-Ras/R-Ras3; The M-Ras/R-Ras-like subfamily contains R-Ras2/TC21, M-Ras/R-Ras3, and related members of the Ras family. M-Ras is expressed in lympho-hematopoetic cells. It interacts with some of the known Ras effectors, but appears to also have its own effectors. Expression of mutated M-Ras leads to transformation of several types of cell lines, including hematopoietic cells, mammary epithelial cells, and fibroblasts. Overexpression of M-Ras is observed in carcinomas from breast, uterus, thyroid, stomach, colon, kidney, lung, and rectum. In addition, expression of a constitutively active M-Ras mutant in murine bone marrow induces a malignant mast cell leukemia that is distinct from the monocytic leukemia induced by H-Ras. TC21, along with H-Ras, has been shown to regulate the branching morphogenesis of ureteric bud cell branching in mice. 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        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   1 MREQYMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRDEFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEAS 80
Cdd:cd04145   66 MREQYMRTGEGFLLVFSVTDRGSFEEVDKFHTQILRVKDRDEFPMILVGNKADLEHQRQVSREEGQELARQLKIPYIETS 145

                         90
                 ....*....|....*....
gi 293597521  81 AKIRMNVDQAFHELVRVIR 99
Cdd:cd04145  146 AKDRVNVDKAFHDLVRVIR 164

Small GTPase of the Ras superfamily; ill-defined subfamily; SMART predicts Ras-like small GTPases of the ARF, RAB, RAN, RAS, and SAR subfamilies. Others that could not be classified in this way are predicted to be members of the small GTPase superfamily without predictions of the subfamily.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521     1 MREQYMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRDEFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEAS 80
Cdd:smart00010  66 MRDQYMRTGEGFLLVYSITDRQSFEEIAKFREQILRVKDRDDVPIVLVGNKCDLENERVVSTEEGKELARQWGCPFLETS 145

                           90       100
                   ....*....|....*....|.
gi 293597521    81 AKIRMNVDQAFHELVRVIRKF 101
Cdd:smart00010 146 AKERINVDEAFYDLVREIRKS 166

Rat sarcoma (Ras) family of small guanosine triphosphatases (GTPases); The Ras family of the Ras superfamily includes classical N-Ras, H-Ras, and K-Ras, as well as R-Ras, Rap, Ral, Rheb, Rhes, ARHI, RERG, Rin/Rit, RSR1, RRP22, Ras2, Ras-dva, and RGK proteins. Ras proteins regulate cell growth, proliferation and differentiation. Ras is activated by guanine nucleotide exchange factors (GEFs) that release GDP and allow GTP binding. Many RasGEFs have been identified. These are sequestered in the cytosol until activation by growth factors triggers recruitment to the plasma membrane or Golgi, where the GEF colocalizes with Ras. Active GTP-bound Ras interacts with several effector proteins: among the best characterized are the Raf kinases, phosphatidylinositol 3-kinase (PI3K), RalGEFs and NORE/MST1. 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        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   1 MREQYMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRDEFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEAS 80
Cdd:cd00876   63 MRDQYIRNGDGFILVYSITSRESFEEIKNIREQILRVKDKEDVPIVLVGNKCDLENERQVSTEEGEALAEEWGCPFLETS 142

                         90
                 ....*....|....*...
gi 293597521  81 AKIRMNVDQAFHELVRVI 98
Cdd:cd00876  143 AKTNINIDELFNTLVREI 160

Ras GTPase family containing H-Ras,N-Ras and K-Ras4A/4B; H-Ras/N-Ras/K-Ras subfamily. H-Ras, N-Ras, and K-Ras4A/4B are the prototypical members of the Ras family. These isoforms generate distinct signal outputs despite interacting with a common set of activators and effectors, and are strongly associated with oncogenic progression in tumor initiation. Mutated versions of Ras that are insensitive to GAP stimulation (and are therefore constitutively active) are found in a significant fraction of human cancers. Many Ras guanine nucleotide exchange factors (GEFs) have been identified. They are sequestered in the cytosol until activation by growth factors triggers recruitment to the plasma membrane or Golgi, where the GEF colocalizes with Ras. Active (GTP-bound) Ras interacts with several effector proteins that stimulate a variety of diverse cytoplasmic signaling activities. Some are known to positively mediate the oncogenic properties of Ras, including Raf, phosphatidylinositol 3-kinase (PI3K), RalGEFs, and Tiam1. Others are proposed to play negative regulatory roles in oncogenesis, including RASSF and NORE/MST1. 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        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   1 MREQYMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRDEFPMILIGNKADLDhQRQVTQEEGQQLARQLKVTYMEAS 80
Cdd:cd04138   65 MRDQYMRTGEGFLCVFAINSRKSFEDIHTYREQIKRVKDSDDVPMVLVGNKCDLA-ARTVSTRQGQDLAKSYGIPYIETS 143

                         90
                 ....*....|....*....
gi 293597521  81 AKIRMNVDQAFHELVRVIR 99
Cdd:cd04138  144 AKTRQGVEEAFYTLVREIR 162

Rat sarcoma (Ras) family 2 of small guanosine triphosphatases (GTPases); The Ras2 subfamily, found exclusively in fungi, was first identified in Ustilago maydis. In U. maydis, Ras2 is regulated by Sql2, a protein that is homologous to GEFs (guanine nucleotide exchange factors) of the CDC25 family. Ras2 has been shown to induce filamentous growth, but the signaling cascade through which Ras2 and Sql2 regulate cell morphology is not known. 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.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   1 MREQYMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRDE--FPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYME 78
Cdd:cd04144   63 LRDQWIREGEGFILVYSITSRSTFERVERFREQIQRVKDESAadVPIMIVGNKCDKVYEREVSTEEGAALARRLGCEFIE 142

                         90       100       110       120
                 ....*....|....*....|....*....|....*....|....*...
gi 293597521  79 ASAKIRMNVDQAFHELVRVIRKFQEQECPPSPEPTRKEKDKKGcHCVI 126
Cdd:cd04144  143 ASAKTNVNVERAFYTLVRALRQQRQGGQGPKGGPTKKKEKKKR-KCVI 189

Rap1 family GTPase consists of Rap1a and Rap1b isoforms; The Rap1 subgroup is part of the Rap subfamily of the Ras family. It can be further divided into the Rap1a and Rap1b isoforms. In humans, Rap1a and Rap1b share 95% sequence homology, but are products of two different genes located on chromosomes 1 and 12, respectively. Rap1a is sometimes called smg p21 or Krev1 in the older literature. Rap1 proteins are believed to perform different cellular functions, depending on the isoform, its subcellular localization, and the effector proteins it binds. For example, in rat salivary gland, neutrophils, and platelets, Rap1 localizes to secretory granules and is believed to regulate exocytosis or the formation of secretory granules. Rap1 has also been shown to localize in the Golgi of rat fibroblasts, zymogen granules, plasma membrane, and the microsomal membrane of pancreatic acini, as well as in the endocytic compartment of skeletal muscle cells and fibroblasts. High expression of Rap1 has been observed in the nucleus of human oropharyngeal squamous cell carcinomas (SCCs) and cell lines; interestingly, in the SCCs, the active GTP-bound form localized to the nucleus, while the inactive GDP-bound form localized to the cytoplasm. Rap1 plays a role in phagocytosis by controlling the binding of adhesion receptors (typically integrins) to their ligands. In yeast, Rap1 has been implicated in multiple functions, including activation and silencing of transcription and maintenance of telomeres. Rap1a, which is stimulated by T-cell receptor (TCR) activation, is a positive regulator of T cells by directing integrin activation and augmenting lymphocyte responses. In murine hippocampal neurons, Rap1b determines which neurite will become the axon and directs the recruitment of Cdc42, which is required for formation of dendrites and axons. In murine platelets, Rap1b is required for normal homeostasis in vivo and is involved in integrin activation. 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        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   1 MREQYMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRDEFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEAS 80
Cdd:cd04175   65 MRDLYMKNGQGFVLVYSITAQSTFNDLQDLREQILRVKDTEDVPMILVGNKCDLEDERVVGKEQGQNLARQWGCAFLETS 144

                         90       100
                 ....*....|....*....|
gi 293597521  81 AKIRMNVDQAFHELVRVIRK 100
Cdd:cd04175  145 AKAKINVNEIFYDLVRQINR 164

Ras-like protein in all tissues (Rit), Ras-like protein in neurons (Rin) and Ras-related protein which interacts with calmodulin (Ric); Rit (Ras-like protein in all tissues), Rin (Ras-like protein in neurons) and Ric (Ras-related protein which interacts with calmodulin) form a subfamily with several unique structural and functional characteristics. These proteins all lack a the C-terminal CaaX lipid-binding motif typical of Ras family proteins, and Rin and Ric contain calmodulin-binding domains. Rin, which is expressed only in neurons, induces neurite outgrowth in rat pheochromocytoma cells through its association with calmodulin and its activation of endogenous Rac/cdc42. Rit, which is ubiquitously expressed in mammals, inhibits growth-factor withdrawl-mediated apoptosis and induces neurite extension in pheochromocytoma cells. Rit and Rin are both able to form a ternary complex with PAR6, a cell polarity-regulating protein, and Rac/cdc42. This ternary complex is proposed to have physiological function in processes such as tumorigenesis. Activated Ric is likely to signal in parallel with the Ras pathway or stimulate the Ras pathway at some upstream point, and binding of calmodulin to Ric may negatively regulate Ric activity.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   1 MREQYMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRDEFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEAS 80
Cdd:cd04141   66 MRDQYMRCGEGFIICYSVTDRHSFQEASEFKELITRVRLTEDIPLVLVGNKVDLEQQRQVTTEEGRNLAREFNCPFFETS 145

                         90       100
                 ....*....|....*....|
gi 293597521  81 AKIRMNVDQAFHELVRVIRK 100
Cdd:cd04141  146 AALRFYIDDAFHGLVREIRR 165

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        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   1 MREQYMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRDEFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEAS 80
Cdd:cd04176   65 MRDLYIKNGQGFIVVYSLVNQQTFQDIKPMRDQIVRVKGYEKVPIILVGNKVDLESEREVSSAEGRALAEEWGCPFMETS 144

                         90
                 ....*....|....*.
gi 293597521  81 AKIRMNVDQAFHELVR 96
Cdd:cd04176  145 AKSKTMVNELFAEIVR 160

Ras-related and Estrogen-Regulated Growth inhibitor (RERG) and Ras-like 11 (RasL11)-like families; RERG (Ras-related and Estrogen- Regulated Growth inhibitor) and Ras-like 11 are members of a novel subfamily of Ras that were identified based on their behavior in breast and prostate tumors, respectively. RERG expression was decreased or lost in a significant fraction of primary human breast tumors that lack estrogen receptor and are correlated with poor clinical prognosis. Elevated RERG expression correlated with favorable patient outcome in a breast tumor subtype that is positive for estrogen receptor expression. In contrast to most Ras proteins, RERG overexpression inhibited the growth of breast tumor cells in vitro and in vivo. RasL11 was found to be ubiquitously expressed in human tissue, but down-regulated in prostate tumors. Both RERG and RasL11 lack the C-terminal CaaX prenylation motif, where a = an aliphatic amino acid and X = any amino acid, and are localized primarily in the cytoplasm. Both are believed to have tumor suppressor activity.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   2 REQYMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRD-EFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEAS 80
Cdd:cd04146   66 LERSLRWADGFVLVYSITDRSSFDVVSQLLQLIREIKKRDgEIPVILVGNKADLLHSRQVSTEEGQKLALELGCLFFEVS 145

                         90       100
                 ....*....|....*....|...
gi 293597521  81 AkiRMNVDQ---AFHELVRVIRK 100
Cdd:cd04146  146 A--AENYLEvqnVFHELCREVRR 166

Ras Homolog Enriched in Brain (RheB) is a small GTPase; Rheb (Ras Homolog Enriched in Brain) subfamily. Rheb was initially identified in rat brain, where its expression is elevated by seizures or by long-term potentiation. It is expressed ubiquitously, with elevated levels in muscle and brain. Rheb functions as an important mediator between the tuberous sclerosis complex proteins, TSC1 and TSC2, and the mammalian target of rapamycin (TOR) kinase to stimulate cell growth. TOR kinase regulates cell growth by controlling nutrient availability, growth factors, and the energy status of the cell. TSC1 and TSC2 form a dimeric complex that has tumor suppressor activity, and TSC2 is a GTPase activating protein (GAP) for Rheb. The TSC1/TSC2 complex inhibits the activation of TOR kinase through Rheb. Rheb has also been shown to induce the formation of large cytoplasmic vacuoles in a process that is dependent on the GTPase cycle of Rheb, but independent of the TOR kinase, suggesting Rheb plays a role in endocytic trafficking that leads to cell growth and cell-cycle progression. 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.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521  11 GFLLVFSVTDRGSFEEIYKFQRQILRVKDRDEFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEASAKIRMNVDQA 90
Cdd:cd04137   75 GYILVYSVTSRKSFEVVKVIYDKILDMLGKESVPIVLVGNKSDLHMERQVSAEEGKKLAESWGAAFLESSAKENENVEEA 154

                         90       100       110
                 ....*....|....*....|....*....|...
gi 293597521  91 FHELVRVIRKFQEqecpPSPEPtrkekDKKGCH 123
Cdd:cd04137  155 FELLIEEIEKVEN----PLPPG-----QKSKCS 178

Ras homolog enriched in striatum (Rhes) and activator of G-protein signaling 1 (Dexras1/AGS1); This subfamily includes Rhes (Ras homolog enriched in striatum) and Dexras1/AGS1 (activator of G-protein signaling 1). These proteins are homologous, but exhibit significant differences in tissue distribution and subcellular localization. Rhes is found primarily in the striatum of the brain, but is also expressed in other areas of the brain, such as the cerebral cortex, hippocampus, inferior colliculus, and cerebellum. Rhes expression is controlled by thyroid hormones. In rat PC12 cells, Rhes is farnesylated and localizes to the plasma membrane. Rhes binds and activates PI3K, and plays a role in coupling serpentine membrane receptors with heterotrimeric G-protein signaling. Rhes has recently been shown to be reduced under conditions of dopamine supersensitivity and may play a role in determining dopamine receptor sensitivity. Dexras1/AGS1 is a dexamethasone-induced Ras protein that is expressed primarily in the brain, with low expression levels in other tissues. Dexras1 localizes primarily to the cytoplasm, and is a critical regulator of the circadian master clock to photic and nonphotic input. 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.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   1 MREQYMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRD--------EFPMILIGNKADLDHQRQVTQEEGQQL-ARQ 71
Cdd:cd04143   64 MRRLSILTGDVFILVFSLDNRESFEEVCRLREQILETKSCLknktkenvKIPMVICGNKADRDFPREVQRDEVEQLvGGD 143

                         90       100       110       120       130       140
                 ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 293597521  72 LKVTYMEASAKIRMNVDQAFHELVRVI-----------RKFQEQECPPSPEPTRKEKDKKG 121
Cdd:cd04143  144 ENCAYFEVSAKKNSNLDEMFRALFSLAklpnemspslhRKISVQYGDALHKKSRGGSRKRK 204

A Ras homolog member I (ARHI); ARHI (A Ras homolog member I) is a member of the Ras family with several unique structural and functional properties. ARHI is expressed in normal human ovarian and breast tissue, but its expression is decreased or eliminated in breast and ovarian cancer. ARHI contains an N-terminal extension of 34 residues (human) that is required to retain its tumor suppressive activity. Unlike most other Ras family members, ARHI is maintained in the constitutively active (GTP-bound) state in resting cells and has modest GTPase activity. ARHI inhibits STAT3 (signal transducers and activators of transcription 3), a latent transcription factor whose abnormal activation plays a critical role in oncogenesis. 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        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   9 GEGFLLVFSVTDRGSFEEIYKFQRQILRVK--DRDEFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEASAKIRMN 86
Cdd:cd04140   73 GHAFILVYSITSKQSLEELKPIYELICEIKgnNLEKIPIMLVGNKCDESPSREVSSSEGAALARTWNCAFMETSAKTNHN 152

                 ....*....
gi 293597521  87 VDQAFHELV 95
Cdd:cd04140  153 VQELFQELL 161

Rab GTPase family 18 (Rab18); Rab18 subfamily. Mammalian Rab18 is implicated in endocytic transport and is expressed most highly in polarized epithelial cells. However, trypanosomal Rab, TbRAB18, is upregulated in the BSF (Blood Stream Form) stage and localized predominantly to elements of the Golgi complex. In human and mouse cells, Rab18 has been identified in lipid droplets, organelles that store neutral lipids. 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        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   5 YMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRDEFPMILIGNKADLDhQRQVTQEEGQQLARQLKVTYMEASAKIR 84
Cdd:cd01863   69 YYRGAQGVILVYDVTRRDTFDNLDTWLNELDTYSTNPDAVKMLVGNKIDKE-NREVTREEGQKFARKHNMLFIETSAKTR 147

                         90
                 ....*....|....
gi 293597521  85 MNVDQAFHELVRVI 98
Cdd:cd01863  148 IGVQQAFEELVEKI 161

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        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   5 YMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRDEFPMiLIGNKADLDHQRQVTQEEGQQLARQLKVTYMEASAKIR 84
Cdd:cd04112   70 YYRDAHALLLLYDVTNKSSFDNIRAWLTEILEYAQSDVVIM-LLGNKADMSGERVVKREDGERLAKEYGVPFMETSAKTG 148

                         90       100       110       120
                 ....*....|....*....|....*....|....*....|..
gi 293597521  85 MNVDQAFHELVRVI--RKFQEQECPPSPEPTRKEKDKKGCHC 124
Cdd:cd04112  149 LNVELAFTAVAKELkhRSVEQPDEPKFKIQDYVEKQKKSSGC 190

Rab GTPase family 3 contains Rab3A, Rab3B, Rab3C and Rab3D; The Rab3 subfamily contains Rab3A, Rab3B, Rab3C, and Rab3D. All four isoforms were found in mouse brain and endocrine tissues, with varying levels of expression. Rab3A, Rab3B, and Rab3C localized to synaptic and secretory vesicles; Rab3D was expressed at high levels only in adipose tissue, exocrine glands, and the endocrine pituitary, where it is localized to cytoplasmic secretory granules. Rab3 appears to control Ca2+-regulated exocytosis. The appropriate GDP/GTP exchange cycle of Rab3A is required for Ca2+-regulated exocytosis to occur, and interaction of the GTP-bound form of Rab3A with effector molecule(s) is widely believed to be essential for this process. Functionally, most studies point toward a role for Rab3 in the secretion of hormones and neurotransmitters. 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        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   5 YMRTGEGFLLVFSVTDRGSFEEIYKFQRQIlRVKDRDEFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEASAKIR 84
Cdd:cd01865   70 YYRGAMGFILMYDITNEESFNAVQDWSTQI-KTYSWDNAQVILVGNKCDMEDERVVSAERGRQLADQLGFEFFEASAKEN 148

                         90
                 ....*....|....
gi 293597521  85 MNVDQAFHELVRVI 98
Cdd:cd01865  149 INVKQVFERLVDII 162

Ras homology family (Rho) of small guanosine triphosphatases (GTPases); Members of the Rho (Ras homology) family include RhoA, Cdc42, Rac, Rnd, Wrch1, RhoBTB, and Rop. There are 22 human Rho family members identified currently. These proteins are all involved in the reorganization of the actin cytoskeleton in response to external stimuli. They also have roles in cell transformation by Ras in cytokinesis, in focal adhesion formation and in the stimulation of stress-activated kinase. These various functions are controlled through distinct effector proteins and mediated through a GTP-binding/GTPase cycle involving three classes of regulating proteins: GAPs (GTPase-activating proteins), GEFs (guanine nucleotide exchange factors), and GDIs (guanine nucleotide dissociation inhibitors). Most Rho 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 Rho proteins. Since crystal structures often lack C-terminal residues, this feature is not available for annotation in many of the CDs in the hierarchy.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521  12 FLLVFSVTDRGSFE--------EIYKFQRQIlrvkdrdefPMILIGNKADL-----------DHQRQVTQEEGQQLARQL 72
Cdd:cd00157   75 FLLCFSVDSPSSFEnvktkwypEIKHYCPNV---------PIILVGTKIDLrddgntlkkleKKQKPITPEEGEKLAKEI 145

                         90       100
                 ....*....|....*....|....*.
gi 293597521  73 K-VTYMEASAKIRMNVDQAFHELVRV 97
Cdd:cd00157  146 GaVKYMECSALTQEGLKEVFDEAIRA 171

Ras - dorsal-ventral anterior localization (Ras-dva) family; Ras-dva subfamily. Ras-dva (Ras - dorsal-ventral anterior localization) subfamily consists of a set of proteins characterized only in Xenopus leavis, to date. In Xenopus Ras-dva expression is activated by the transcription factor Otx2 and begins during gastrulation throughout the anterior ectoderm. Ras-dva expression is inhibited in the anterior neural plate by factor Xanf1. Downregulation of Ras-dva results in head development abnormalities through the inhibition of several regulators of the anterior neural plate and folds patterning, including Otx2, BF-1, Xag2, Pax6, Slug, and Sox9. Downregulation of Ras-dva also interferes with the FGF-8a signaling within the anterior ectoderm. 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.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   1 MREQYMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRDEFPMILIGNKADLDHQRQVTQEEGQQLAR-QLKVTYMEA 79
Cdd:cd04147   63 MRKLSIQNGDAFALVYSVDDPESFEEVKRLREEILEVKEDKFVPIVVVGNKIDSLAERQVEAADALSTVElDWNNGFVEA 142

                         90
                 ....*....|....*..
gi 293597521  80 SAKIRMNVDQAFHELVR 96
Cdd:cd04147  143 SAKDNENVTEVFKELLQ 159

Rab family protein; Provisional

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   5 YMRTGEGFLLVFSVTDRGSFEEIYK-FQRQILRVKDRDEFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEASAKI 83
Cdd:PLN03118  82 YYRNAQGIILVYDVTRRETFTNLSDvWGKEVELYSTNQDCVKMLVGNKVDRESERDVSREEGMALAKEHGCLFLECSAKT 161

                         90
                 ....*....|.
gi 293597521  84 RMNVDQAFHEL 94
Cdd:PLN03118 162 RENVEQCFEEL 172

Rho (Ras homology) subfamily of Ras-like small GTPases; Members of this subfamily of Ras-like small GTPases include Cdc42 and Rac, as well as Rho isoforms.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521    12 FLLVFSVTDRGSFEEI-YKFQRQILrvkdrdEF----PMILIGNKADL----------DHQRQ--VTQEEGQQLARQLK- 73
Cdd:smart00174  73 FLICFSVDSPASFENVkEKWYPEVK------HFcpnvPIILVGTKLDLrndkstleelSKKKQepVTYEQGQALAKRIGa 146

                           90       100
                   ....*....|....*....|....*
gi 293597521    74 VTYMEASAKIRMNVDQAFHELVRVI 98
Cdd:smart00174 147 VKYLECSALTQEGVREVFEEAIRAA 171

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        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521  14 LVFSVTDRGSFEEIykfQRQILRVKDR--DEFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEASAKIRMNVDQAF 91
Cdd:cd01861   78 VVYDITNRQSFDNT---DKWIDDVRDErgNDVIIVLVGNKTDLSDKRQVSTEEGEKKAKENNAMFIETSAKAGHNVKQLF 154

Rab GTPase; Provisional

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   5 YMRTGEGFLLVFSVTDRGSFEEIYKFQRQiLRVKDRDEFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEASAKIR 84
Cdd:PLN03110  81 YYRGAVGALLVYDITKRQTFDNVQRWLRE-LRDHADSNIVIMMAGNKSDLNHLRSVAEEDGQALAEKEGLSFLETSALEA 159

                         90       100
                 ....*....|....*....|
gi 293597521  85 MNVDQAFH----ELVRVIRK 100
Cdd:PLN03110 160 TNVEKAFQtillEIYHIISK 179

Rab GTPase family 14 (Rab14); Rab14 GTPases are localized to biosynthetic compartments, including the rough ER, the Golgi complex, and the trans-Golgi network, and to endosomal compartments, including early endosomal vacuoles and associated vesicles. Rab14 is believed to function in both the biosynthetic and recycling pathways between the Golgi and endosomal compartments. Rab14 has also been identified on GLUT4 vesicles, and has been suggested to help regulate GLUT4 translocation. In addition, Rab14 is believed to play a role in the regulation of 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        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   5 YMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRDEFpMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEASAKIR 84
Cdd:cd04122   71 YYRGAAGALMVYDITRRSTYNHLSSWLTDARNLTNPNTV-IFLIGNKADLEAQRDVTYEEAKQFADENGLLFLECSAKTG 149

                         90
                 ....*....|....
gi 293597521  85 MNVDQAFHELVRVI 98
Cdd:cd04122  150 ENVEDAFLETAKKI 163

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        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   5 YMRTGEGFLLVFSVTDRGSFEEIYKFqrqilrVKDRDE----FPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEAS 80
Cdd:cd04121   75 YSRGAQGIILVYDITNRWSFDGIDRW------IKEIDEhapgVPKILVGNRLHLAFKRQVATEQAQAYAERNGMTFFEVS 148

                         90       100       110
                 ....*....|....*....|....*....|....*
gi 293597521  81 AKIRMNVDQAFHELVR-VIRKFQEQECPPSPEPTR 114
Cdd:cd04121  149 PLCNFNITESFTELARiVLMRHGRPPQSPPQNCSR 183

Rab GTPase family 23 (Rab23)-like; Rab23-like subfamily. Rab23 is a member of the Rab family of small GTPases. In mouse, Rab23 has been shown to function as a negative regulator in the sonic hedgehog (Shh) signaling pathway. Rab23 mediates the activity of Gli2 and Gli3, transcription factors that regulate Shh signaling in the spinal cord, primarily by preventing Gli2 activation in the absence of Shh ligand. Rab23 also regulates a step in the cytoplasmic signal transduction pathway that mediates the effect of Smoothened (one of two integral membrane proteins that are essential components of the Shh signaling pathway in vertebrates). In humans, Rab23 is expressed in the retina. Mice contain an isoform that shares 93% sequence identity with the human Rab23 and an alternative splicing isoform that is specific to the brain. This isoform causes the murine open brain phenotype, indicating it may have a role in the development of the central nervous system. 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        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   5 YMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDrdEFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTYMEASAKIR 84
Cdd:cd04106   71 YYRGAQACILVFSTTDRESFEAIESWKEKVEAECG--DIPMVLVQTKIDLLDQAVITNEEAEALAKRLQLPLFRTSVKDD 148

                 ....*..
gi 293597521  85 MNVDQAF 91
Cdd:cd04106  149 FNVTELF 155

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        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   3 EQYMRTGEGFLLVFSVTDRGSFEEIYKFQRQILRVKDRDeFPMILIGNKADLDHQRQVTQEEGQQLARQLKVTY-MEASA 81
Cdd:cd01864   70 QSYYRSANGAIIAYDITRRSSFESVPHWIEEVEKYGASN-VVLLLIGNKCDLEEQREVLFEEACTLAEHYGILAvLETSA 148

                         90
                 ....*....|....*
gi 293597521  82 KIRMNVDQAFHELVR 96
Cdd:cd01864  149 KESSNVEEAFLLMAT 163

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        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 293597521   3 EQYMRTGEGFLLVFSVTDRGSFEEIYKFqrqilrVKDRDEF-----PMILIGNKADLDHQRQVTQEEGQQLARQLKVTYM 77
Cdd:cd04117   67 KQYYRRAQGIFLVYDISSERSYQHIMKW------VSDVDEYapegvQKILIGNKADEEQKRQVGDEQGNKLAKEYGMDFF 140