title: GTPase-activating proteins and their complexes.
abstract: In the past year, crystallographic structures for four complexes of GTPase-activating proteins (GAPs) with their target G proteins have been described and substantially enhance our understanding of how these proteins function. GAPs specific for the Rho and Ras families of small G proteins insert an arginine residue into the active site of the G protein, stabilise its switch regions and share an underlying topological relationship. The complex of a heterotrimeric G protein with its activating protein shows that the latter protein does not participate directly in the hydrolytic reaction and has a different structure of RhoGAP and RasGAP.
authors.affiliation: Protein Structure Division, National Institute for Medical Research, London, UK. s-gambli@anika.nimr.mrc.ac.uk
authors.forename: S J
authors.initials: SJ
authors.lastname: Gamblin
authors.forename: S J
authors.initials: SJ
authors.lastname: Smerdon
mesh_terms: D000818:Animals; D001665:Binding Sites; D004789:Enzyme Activation; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D006801:Humans; D046911:Macromolecular Substances; D008958:Models, Molecular; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*; D020703:ras GTPase-Activating Proteins
chemical_list: D020690:GTPase-Activating Proteins; D046911:Macromolecular Substances; D011506:Proteins; D020703:ras GTPase-Activating Proteins; C085379:rho GTPase-activating protein; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins