Coupling of glucagon receptor to adenylyl cyclase. Requirement of a receptor-related guanyl nucleotide binding site for coupling of receptor to the enzyme.
Year: 1979
Type: article
Abstract: Effects of glucagon and guanyl nucleotides on the rat liver plasma membrane adenylyl cyclase were studied. It was established that: 1) glucagon stimulates the fully guanyl-5'-yl imidodiphosphate (GMP-P(NH)P)-activated enzyme between 20 and 70%, provided a guanyl nucleotide is present in the assay; 2) glucagon has no effect on adenylyl cyclase activity in membranes activated fully by GMP-P(NH)P and then washed free of nucleotides. It is concluded that occupancy of the guanyl nucleotide binding site that activates the catalytic moiety of the system is not sufficient to promote hormone-receptor coupling to adenylyl cyclase and that occupancy of a second site by guanyl nucleotides is essential to effect stimulation of adenylyl cyclase by the glucagon-receptor complex. The data presented raise the question whether the guanyl nucleotide site that promotes coupling is distinct from the guanyl nucleotide site that modulates binding of glucagon to receptor and whether the occupancy of the guanyl nucleotide site associated with the catalytic moiety is necessary for coupling.
Source: Journal of Biological Chemistry
Authors: R. Iyengar, T.L. Swartz, L. Birnbaumer
Institution: Baylor College of Medicine
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
Funder: National Institutes of Health
OpenAlex ID: W1562204756