p115 RhoGEF, a GTPase activating protein for Gα₁₂ and Gα₁₃

Members of the regulators of G protein signaling (RGS) family stimulate the intrinsic guanosine triphosphatase (GTPase) activity of the α subunits of certain heterotrimeric guanine nucleotide-binding proteins (G proteins). The guanine nucleotide exchange factor (GEF) for Rho, p115 RhoGEF, has an amino-terminal region with similarity to RGS proteins. Recombinant p115 RhoGEF and a fusion protein containing the amino terminus of p115 had specific activity as GTPase activating proteins toward the α subunits of the G proteins G₁₂ and G₁₃, but not toward members of the G(s), G(i), or G(q) subfamilies of Gα proteins. This GEF may act as an intermediary in the regulation of Rho proteins by G₁₃ and G₁₂.