Interaction of G protein G beta gamma dimers with small GTP-binding proteins of the Rho family

G beta gamma dimers of heterotrimeric G proteins have been shown to be important for the translocation of cytosolic proteins to membranes, The involvement of G beta gamma in those signaling processes mediated by small GTP-binding proteins of the Rho family was studied using purified proteins, We showed specific binding of bovine brain G beta gamma to immobilized GST-Rho fusion proteins, In addition, brain G beta gamma, but not transducin G beta gamma, was able to inhibit GTP gamma S binding to GST-Rho in a concentration-dependent manner, GTP gamma S binding to GST-Rac was also decreased by brain G beta gamma whereas nucleotide binding to GST-Cdc42 was not changed, We conclude that G beta gamma dimers may participate in the process of membrane attachment and/or other regulations of Rho and Rac.