The core domain of RGS16 retains G-protein binding and GAP activity in vitro, but is not functional in vivo

The regulators of G-protein signaling (RGS) family members contain a conserved region, the RGS domain, and are GTPase-activating proteins for many members of G-protein alpha-subunits, We report here that the core domain of RGS16 is sufficient for in vitro biochemical functions as assayed by its G-protein binding affinity and its ability to stimulate GTP hydrolysis by G alpha(o) protein, RGS16 also requires, in addition to the RGS domain, the divergent N-terminus for its biological function in the attenuation of pheromone signaling in yeast, whereas its C-terminus region is dispensable, Together with other evidence, these data support the notion that RGS proteins interact with other cellular factors and may serve to link specific G-proteins to different downstream effecters in G-protein-mediated signaling pathways. (C) 1998 Federation of European Biochemical Societies.