Effects of cholera toxin and guanosine 5'-[betagamma-imido]triphosphate on beta-adrenergic-receptor affinity.
A comparison was made of the effects of cholera toxin and p[NH]ppG on the binding affinity of beta-adrenergic receptors in toad erythrocyte membranes. This was determined by studying the ability of isoproterenol and propranolol to compete for the receptor with (-)-[3H]dihydroalprenolol. p[NH]ppG decreased the receptor affinity for the agonist isoproterenol (i.e. a 'right' shift in the displacement-concentration curve), but was without effect on the affinity for the antagonist propranolol. Toad erythrocyte membranes after treatment with cholera toxin exhibited increased receptor affinity for isoproterenol (i.e. a 'left' shift in the displacement curve), but did not affect the affinity for propranolol. p[NH[ppG was able to exert its right shift even in cholera-toxin treated membranes. The ability of cholera toxin to alter beta-adrenergic-receptor affinity is interpreted as further evidence that the toxin affects the nucleotide-regulatory component of adenylate cyclase. The regulatory component affected may be the catecholamine-sensitive guanosine triphosphatase.
D000526:Alprenolol / Q000378:metabolism; D000818:Animals; D001001:Anura; D002772:Cholera Toxin / Q000494:pharmacology*; D004910:Erythrocyte Membrane / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives*; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology*; D007545:Isoproterenol / Q000378:metabolism; D011433:Propranolol / Q000378:metabolism; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects* / Q000378:metabolism
D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D006165:Guanylyl Imidodiphosphate; D006160:Guanosine Triphosphate; D000526:Alprenolol; D002772:Cholera Toxin; D011433:Propranolol; D007545:Isoproterenol