A typical G-protein is active when bound to GTP and inactive when bound to GDP (i.e. when the GTP is hydrolyzed to GDP). The GDP can be then replaced by free GTP. Therefore, a G-protein can be switched on and off. GTP hydrolysis is accelerated by GTPase activating proteins (GAPs), while GTP exchange is catalyzed by guanine nucleotide exchange factors (GEFs). Activation of a GEF typically activates its cognate G-protein, while activation of a GAP results in inactivation of the cognate G-protein. Guanosine nucleotide dissociation inhibitors (GDI) maintain small GTPases in the inactive state.
There are more than a hundred proteins in the Ras superfamily.[1] Based on structure, sequence and function, the Ras superfamily is divided into five main families, (Ras, Rho, Ran, Rab and Arf GTPases).[2] The Ras family itself is further divided into 6 subfamilies: Ras, Ral, Rit, Rap, Rheb, and Rad. Miro is a recent contributor to the superfamily.[citation needed]
Each subfamily shares the common core G domain, which provides essential GTPase and nucleotide exchange activity.[citation needed]
The surrounding sequence helps determine the functional specificity of the small GTPase, for example the 'Insert Loop', common to the Rho subfamily, specifically contributes to binding to effector proteins such as IQGAP and WASP.[citation needed]
The Ras family is generally responsible for cell proliferation, Rho for cell morphology, Ran for nuclear transport and Rab and Arf for vesicle transport.[3]
^Wennerberg K, Rossman KL, Der CJ (March 2005). "The Ras superfamily at a glance". J. Cell Sci. 118 (Pt 5): 843–6. doi:10.1242/jcs.01660. PMID 15731001.
^Goitre, L; Trapani, E; Trabalzini, L; Retta, SF (26 December 2013). The Ras superfamily of small GTPases: the unlocked secrets. Methods in Molecular Biology. Vol. 1120. pp. 1–18. doi:10.1007/978-1-62703-791-4_1. ISBN978-1-62703-790-7. PMID 24470015.
^Munemitsu S, Innis M, Clark R, McCormick F, Ullrich A, Polakis P (1990). "Molecular cloning and expression of a G25K cDNA, the human homolog of the yeast cell cycle gene CDC42". Mol Cell Biol. 10 (11): 5977–82. doi:10.1128/MCB.10.11.5977. ISSN 0270-7306. PMC361395. PMID 2122236.
small, gtpase, also, known, small, proteins, family, hydrolase, enzymes, that, bind, hydrolyze, guanosine, triphosphate, they, type, protein, found, cytosol, that, homologous, alpha, subunit, heterotrimeric, proteins, unlike, alpha, subunit, proteins, small, g. Small GTPases EC 3 6 5 2 also known as small G proteins are a family of hydrolase enzymes that can bind and hydrolyze guanosine triphosphate GTP They are a type of G protein found in the cytosol that are homologous to the alpha subunit of heterotrimeric G proteins but unlike the alpha subunit of G proteins a small GTPase can function independently as a hydrolase enzyme to bind to and hydrolyze a guanosine triphosphate GTP to form guanosine diphosphate GDP The best known members are the Ras GTPases and hence they are sometimes called Ras subfamily GTPases Small monomeric GTPaseIdentifiersEC no 3 6 5 2DatabasesIntEnzIntEnz viewBRENDABRENDA entryExPASyNiceZyme viewKEGGKEGG entryMetaCycmetabolic pathwayPRIAMprofilePDB structuresRCSB PDB PDBe PDBsumSearchPMCarticlesPubMedarticlesNCBIproteins A typical G protein is active when bound to GTP and inactive when bound to GDP i e when the GTP is hydrolyzed to GDP The GDP can be then replaced by free GTP Therefore a G protein can be switched on and off GTP hydrolysis is accelerated by GTPase activating proteins GAPs while GTP exchange is catalyzed by guanine nucleotide exchange factors GEFs Activation of a GEF typically activates its cognate G protein while activation of a GAP results in inactivation of the cognate G protein Guanosine nucleotide dissociation inhibitors GDI maintain small GTPases in the inactive state Small GTPases regulate a wide variety of processes in the cell including growth cellular differentiation cell movement and lipid vesicle transport Contents 1 The Ras superfamily 2 See also 3 References 4 External linksThe Ras superfamily editMain article Ras superfamily There are more than a hundred proteins in the Ras superfamily 1 Based on structure sequence and function the Ras superfamily is divided into five main families Ras Rho Ran Rab and Arf GTPases 2 The Ras family itself is further divided into 6 subfamilies Ras Ral Rit Rap Rheb and Rad Miro is a recent contributor to the superfamily citation needed Each subfamily shares the common core G domain which provides essential GTPase and nucleotide exchange activity citation needed The surrounding sequence helps determine the functional specificity of the small GTPase for example the Insert Loop common to the Rho subfamily specifically contributes to binding to effector proteins such as IQGAP and WASP citation needed The Ras family is generally responsible for cell proliferation Rho for cell morphology Ran for nuclear transport and Rab and Arf for vesicle transport 3 See also editGTP binding protein regulatorsReferences edit Wennerberg K Rossman KL Der CJ March 2005 The Ras superfamily at a glance J Cell Sci 118 Pt 5 843 6 doi 10 1242 jcs 01660 PMID 15731001 Goitre L Trapani E Trabalzini L Retta SF 26 December 2013 The Ras superfamily of small GTPases the unlocked secrets Methods in Molecular Biology Vol 1120 pp 1 18 doi 10 1007 978 1 62703 791 4 1 ISBN 978 1 62703 790 7 PMID 24470015 Munemitsu S Innis M Clark R McCormick F Ullrich A Polakis P 1990 Molecular cloning and expression of a G25K cDNA the human homolog of the yeast cell cycle gene CDC42 Mol Cell Biol 10 11 5977 82 doi 10 1128 MCB 10 11 5977 ISSN 0270 7306 PMC 361395 PMID 2122236 External links editSmall GTPases at the U S National Library of Medicine Medical Subject Headings MeSH Portal nbsp Biology Retrieved from https en wikipedia org w index php title Small GTPase amp oldid 1181172692, wikipedia, wiki, book, books, library,
