Correlation of β-adrenergic receptor-stimulated [³H]GDP release and adenylate cyclase activation. Differences between frog and turkey erythrocyte membranes

The mechanism by which β-adrenergic agents stimulate adenylate cyclase activity appears to involve the catecholamine-induced release of GDP from the nucleotide regulatory protein. Using the assay developed by Cassel and Selinger [(1978) Proc. Natl. Acad. Sci. U.S.A. 75, 4155-4159], the characteristics of catecholamine-stimulated [³H]GDP release in frog and turkey erythrocyte membranes were examined. The release of [³H]GDP from turkey erythrocyte membranes was significantly slower than from frog erythrocyte membranes. In addition, the exchange of the diphosphate was absolutely dependent on the presence of isoproterenol in turkey erythrocyte membranes, but was merely facilitated by the agonist in frog erythrocyte membranes. The isoproterenol-stimulated release of [³H]GDP in both systems could be blocked by propranolol but not by phentolamine. β-Adrenergic agonists demonstrated equivalent intrinsic activities for the stimulation of GDP release and adenylate cyclase activity and the different patterns of agonist intrinsic activities observed in frog and turkey erythrocytes were maintained in both the GDP release and adenylate cyclase assays. Prostaglandin E₁, which stimulates the adenylate cyclase in frog erythrocyte membranes, also induced the release of GDP from these membrane preparations and exhibited a similar intrinsic activity for GDP release and adenylate cyclase activation. Since prostaglandin E₁ was able to release the nucleotide loaded in the presence of the β-agonist, isoproterenol, these data suggest that the prostaglandin and β-adrenergic receptors share a common pool of nucleotide regulatory proteins in these cells.