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.
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Research Article| November 15 1978
Effects of cholera toxin and guanosine 5′-[βγ-imido]triphosphate on β-adrenergic-receptor affinity
Biochem J (1978) 176 (2): 505–510.
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J Fischer, G W G Sharp; Effects of cholera toxin and guanosine 5′-[βγ-imido]triphosphate on β-adrenergic-receptor affinity. Biochem J 15 November 1978; 176 (2): 505–510. doi: https://doi.org/10.1042/bj1760505
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