title: Rac GTPase interacts with GAPs and target proteins through multiple effector sites.
abstract: Rac, a small GTPase in the ras superfamily, regulates at least two biological processes in animal cells: (i) the polymerization of actin and the assembly of integrin complexes to produce lamellipodia and ruffles; and (ii) the activity of an NADPH oxidase in phagocytic cells. NADPH oxidase activation is mediated through a rac effector protein, p67phox, and using chimeras made between rac and the closely related GTPase, rho, we have identified two distinct effector sites in rac, one N-terminal and one C-terminal, both of which are required for activation of p67phox. The same two effector sites are essential for rac-induced actin polymerization in fibroblasts. p65PAK, a ubiquitous serine/threonine kinase, interacts with rac at both the N- and C-terminal effector sites, but the GTPase-activating protein, bcr interacts with rac at a different region. This makes p65PAK, but not bcr, a candidate effector of rac-induced lamellipodium formation.
mesh_terms: D016475:3T3 Cells; D000199:Actins / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D051379:Mice; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D019255:NADPH Oxidases; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020744:rac GTP-Binding Proteins; D020703:ras GTPase-Activating Proteins
chemical_list: D000199:Actins; D020690:GTPase-Activating Proteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; D020703:ras GTPase-Activating Proteins; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; D017346:Protein Serine-Threonine Kinases; D019204:GTP-Binding Proteins; D020744:rac GTP-Binding Proteins