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 1229732590  22 VKIICLGDSAVGKSKLMERFLMDGFQPQQLSTYALTLYKHTATVDGKTILV----------------------------- 72
Cdd:cd04124     1 VKIILLGDSAVGKSKLVERFLMDGYEPQQLSTYALTLYKHNAKFEGKTILVdfwdtagqerfqtmhasyyhkahacilvf 80

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1229732590  73 -----------------------------------ADINVTQKSFNFAKKFSLPLYFVSAADGTNVVkvwltaevasKLF 117
Cdd:cd04124    81 dvtrkityknlskwyeelreyrpeipcivvankidLDPSVTQKKFNFAEKHNLPLYYVSAADGTNVV----------KLF 150

                         170
                  ....*....|.
gi 1229732590 118 NDAIRLAVSYK 128
Cdd:cd04124   151 QDAIKLAVSYK 161

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        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1229732590  22 VKIICLGDSAVGKSKLMERFLMDGFQPQQLSTYALTLYKHTATVDGKTILV----------------------------- 72
Cdd:cd04124     1 VKIILLGDSAVGKSKLVERFLMDGYEPQQLSTYALTLYKHNAKFEGKTILVdfwdtagqerfqtmhasyyhkahacilvf 80

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1229732590  73 -----------------------------------ADINVTQKSFNFAKKFSLPLYFVSAADGTNVVkvwltaevasKLF 117
Cdd:cd04124    81 dvtrkityknlskwyeelreyrpeipcivvankidLDPSVTQKKFNFAEKHNLPLYYVSAADGTNVV----------KLF 150

                         170
                  ....*....|.
gi 1229732590 118 NDAIRLAVSYK 128
Cdd:cd04124   151 QDAIKLAVSYK 161

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

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|....*....
gi 1229732590   22 VKIICLGDSAVGKSKLMERFLMDGFQPQQLSTYALTLYKHTATVDGKTI 70
Cdd:smart00175   1 FKIILIGDSGVGKSSLLSRFTDGKFSEQYKSTIGVDFKTKTIEVDGKRV 49

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        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1229732590  22 VKIICLGDSAVGKSKLMERFLMDGFQPQQLSTYALTLYKHTATVDGKTILV----------------------------- 72
Cdd:cd04124     1 VKIILLGDSAVGKSKLVERFLMDGYEPQQLSTYALTLYKHNAKFEGKTILVdfwdtagqerfqtmhasyyhkahacilvf 80

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1229732590  73 -----------------------------------ADINVTQKSFNFAKKFSLPLYFVSAADGTNVVkvwltaevasKLF 117
Cdd:cd04124    81 dvtrkityknlskwyeelreyrpeipcivvankidLDPSVTQKKFNFAEKHNLPLYYVSAADGTNVV----------KLF 150

                         170
                  ....*....|.
gi 1229732590 118 NDAIRLAVSYK 128
Cdd:cd04124   151 QDAIKLAVSYK 161

Ras-related in brain (Rab) family of small guanosine triphosphatases (GTPases); Rab GTPases form the largest family within the Ras superfamily. There are at least 60 Rab genes in the human genome, and a number of Rab GTPases are conserved from yeast to humans. Rab GTPases are small, monomeric proteins that function as molecular switches to regulate vesicle trafficking pathways. The different Rab GTPases are localized to the cytosolic face of specific intracellular membranes, where they regulate distinct steps in membrane traffic pathways. In the GTP-bound form, Rab GTPases recruit specific sets of effector proteins onto membranes. Through their effectors, Rab GTPases regulate vesicle formation, actin- and tubulin-dependent vesicle movement, and membrane fusion. 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 mask C-terminal lipid binding and promote cytosolic localization. While most unicellular organisms possess 5-20 Rab members, several have been found to possess 60 or more Rabs; for many of these Rab isoforms, homologous proteins are not found in other organisms. 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. Since crystal structures often lack C-terminal residues, the lipid modification site is not available for annotation in many of the CDs in the hierarchy, but is included where possible.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*....
gi 1229732590  22 VKIICLGDSAVGKSKLMERFLMDGFQPQQLSTYALTLYKHTATVDGKTI 70
Cdd:cd00154     1 FKIVLIGDSGVGKTSLLLRFVDNKFSENYKSTIGVDFKSKTIEVDGKKV 49

Ras family; Includes sub-families Ras, Rab, Rac, Ral, Ran, Rap Ypt1 and more. Shares P-loop motif with GTP_EFTU, arf and myosin_head. See pfam00009 pfam00025, pfam00063. As regards Rab GTPases, these are important regulators of vesicle formation, motility and fusion. They share a fold in common with all Ras GTPases: this is a six-stranded beta-sheet surrounded by five alpha-helices.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*....
gi 1229732590  23 KIICLGDSAVGKSKLMERFLMDGFQPQQLSTYALTLYKHTATVDGKTIL 71
Cdd:pfam00071   1 KLVLVGDGGVGKSSLLIRFTQNKFPEEYIPTIGVDFYTKTIEVDGKTVK 49

Rab GTPase family 11 (Rab11)-like includes Rab11a, Rab11b, and Rab25; Rab11a, Rab11b, and Rab25 are closely related, evolutionary conserved Rab proteins that are differentially expressed. Rab11a is ubiquitously synthesized, Rab11b is enriched in brain and heart and Rab25 is only found in epithelia. Rab11/25 proteins seem to regulate recycling pathways from endosomes to the plasma membrane and to the trans-Golgi network. Furthermore, Rab11a is thought to function in the histamine-induced fusion of tubulovesicles containing H+, K+ ATPase with the plasma membrane in gastric parietal cells and in insulin-stimulated insertion of GLUT4 in the plasma membrane of cardiomyocytes. Overexpression of Rab25 has recently been observed in ovarian cancer and breast cancer, and has been correlated with worsened outcomes in both diseases. In addition, Rab25 overexpression has also been observed in prostate cancer, transitional cell carcinoma of the bladder, and invasive breast tumor cells. 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 1229732590  23 KIICLGDSAVGKSKLMERFLMDGFQPQQLSTYALTLYKHTATVDGKTI 70
Cdd:cd01868     5 KIVLIGDSGVGKSNLLSRFTRNEFNLDSKSTIGVEFATRTIQIDGKTI 52

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
                  ....*....|....*....|....*....|....*....|....*...
gi 1229732590  23 KIICLGDSAVGKSKLMERFLMDGFQPQQLSTYALTLYKHTATVDGKTI 70
Cdd:cd01861     2 KLVFLGDQSVGKTSIITRFMYDTFDNQYQATIGIDFLSKTMYVDDKTV 49

Rab GTPase family 9 (Rab9); Rab9 is found in late endosomes, together with mannose 6-phosphate receptors (MPRs) and the tail-interacting protein of 47 kD (TIP47). Rab9 is a key mediator of vesicular transport from late endosomes to the trans-Golgi network (TGN) by redirecting the MPRs. Rab9 has been identified as a key component for the replication of several viruses, including HIV1, Ebola, Marburg, and measles, making it a potential target for inhibiting a variety of viruses. 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 1229732590  22 VKIICLGDSAVGKSKLMERFLMDGFQPQQLSTYALTLYKHTATVDGK 68
Cdd:cd04116     6 LKVILLGDGGVGKSSLMNRYVTNKFDTQLFHTIGVEFLNKDLEVDGH 52

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
                  ....*....|....*....|....*....|....*....|....*...
gi 1229732590  23 KIICLGDSAVGKSKLMERFLMDGFQPQQLSTYALTLYKHTATVDGKTI 70
Cdd:cd01867     5 KLLLIGDSGVGKSCLLLRFSEDSFNPSFISTIGIDFKIRTIELDGKKI 52

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 1229732590  22 VKIICLGDSAVGKSKLMERFLMDGFQPQQLSTYALTLYKHTATVDGK---TILVADI 75
Cdd:cd04109     1 IKIVVLGDGASGKTSLIRRFAQEGFGKSYKQTIGLDFFSRRITLPGSlnvTLQVWDI 57

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
                  ....*....|....*....|....*....|....*....|....*....|.
gi 1229732590  23 KIICLGDSAVGKSKLMERFLMDGFqpqqLSTYALT---LYKHTATVDGKTI 70
Cdd:cd04146     1 KIAVLGASGVGKSALTVRFLTKRF----IGEYEPNlesLYSRQVTIDGEQV 47