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, T he involvement of G beta gamma in those signaling processes mediated b y small GTP-binding proteins of the Rho family was studied using purif ied proteins, We showed specific binding of bovine brain G beta gamma to immobilized GST-Rho fusion proteins, In addition, brain G beta gamm a, but not transducin G beta gamma, was able to inhibit GTP gamma S bi nding to GST-Rho in a concentration-dependent manner, GTP gamma S bind ing to GST-Rac was also decreased by brain G beta gamma whereas nucleo tide binding to GST-Cdc42 was not changed, We conclude that G beta gam ma dimers may participate in the process of membrane attachment and/or other regulations of Rho and Rac.