Interaction of β-adrenergic receptors with the inhibitory guanine nucleotide-binding protein of adenylate cyclase in membranes prepared from cyc^- S49 lymphoma cells

β-Adrenergic receptors on membranes prepared from L6 myoblasts, wild-type S49 lymphoma cells, and an adenylate cyclase-deficient variant (cyc^-) of S49 lymphoma cells bind the agonist [³H]hydroxybenzylisoproterenol ([³H]HBI) with high affinity. In each case the agonist [³H]HBI is associated with a larger complex than is the antagonist [¹²⁵I]iodopindolol, and the binding of [³H]HBI can be inhibited by GTP. These observations suggest that there is an agonist-dependent association of the receptor with a guanine nucleotide-binding protein. The goal of the present experiments was to investigate the possibility that an interaction of β-adrenergic receptors with the inhibitory guanine nucleotide-binding protein of adenylate cyclase was responsible for these observations. Treatment of S49 cells with pertussis toxin decreased the extent of pertussis toxin-catalyzed [³²P]ADP-ribosylation of a 41,000-dalton protein, measured in vitro, and decreased the inhibition of adenylate cyclase activity observed in the presence of somatostatin or analogues of GTP. Isoproterenol-stimulated adenylate cyclase activity was potentiated following treatment of wild-type S49 cells and L6 myoblasts with pertussis toxin. Although the ability of receptors on membranes prepared from L6 myoblasts to bind the agonist [³H]HBI was not affected by treatment of cells with pertussis toxin, treatment of cyc^- S49 cells with pertussis toxin markedly decreased the ability of receptors to bind [³H]HBI. The observed inhibition of the binding of the agonist [³H]HBI to β-adrenergic receptors on membranes prepared from cyc^- S49 cells after treatment with pertussis toxin could be explained by an interaction between β-adrenergic receptors and the inhibitory guanine nucleotide-binding protein. Such an interaction may represent a mechanism through which stimulation of the activity of adenylate cyclase by β-adrenergic receptors can be regulated or through which β-adrenergic receptors can affect the activity of cyclic AMP-independent cellular processes.