Receptor and effector interactions of G_s Functional studies with antibodies to the α_s carboxyl-terminal decapeptide

Antibodies generated to a synthetic decapeptide, RMHLRQYELL, representing the carboxyl-terminus of G_s-α have been characterized in immunoblots and functional studies. This antibody, designated RM, reacts exclusively with a doublet of proteins of 52 and 45 kDa in immunoblots of bovine brain and wild-type S49 murine lymphoma cell membranes. No such reactivity is seen in membranes from cyc^- S49 cells, which lack G_s. RM blocks receptor-mediated activation of G_s and adenylyl cyclase in membranes from wild-type S49 cells. RM could also immunoprecipitate adenylyl cyclase activity in detergent extracts from GTP[γ]S- or fluoride-preactivated bovine brain membranes; thus binding of α_s to effector and carboxyl-terminal antibody was mutually compatible. Such experiments provide an approach for the elucidation of functionally relevant interactions of G-proteins with receptors and electors in the membrane.