Affordable Access

Publisher Website

Basal and hormone-stimulated adenylate cyclase in liver plasma membranes: Measurement by radioimmunoassay of cyclic AMP

Authors
Journal
Biochimica et Biophysica Acta (BBA) - General Subjects
0304-4165
Publisher
Elsevier
Publication Date
Volume
304
Issue
2
Identifiers
DOI: 10.1016/0304-4165(73)90275-4
Disciplines
  • Biology

Abstract

Abstract A radioimmunoassay technique for cyclic AMP has been applied to the assay of adenylate cyclase activity in liver plasma membranes by measuring the amount of cyclic AMP produced from ATP. This procedure is highly specific and sensitive and allows the measurement of nM concentrations of cyclic AMP in the presence of mM concentrations of ATP. The basal adenylate cyclase activity is proportional to the membrane concentration in the range of 50–400 μg of membrane protein per ml. Both the basal and the glucagon-stimulated activities of the enzyme depend on the concentration of ATP, with an optimum at 0.8–1.0 mM ATP in the presence of 5 mM Mg 2+ and an apparent K m of approx. 0.4 mM. Adenylate cyclase activity is stimulated by glucagon over a range of 0.05–10 nM, and is increased 10–20-fold by maximally stimulating concentrations of the hormone. Insulin did not alter either the basal or the glucagon-stimulated activity of the enzyme under a variety of experimental conditions including various concentrations of ATP and of the hormones. Insulin did not modify the degree of inhibition of adenylate cyclase produced by Ca 2+.

There are no comments yet on this publication. Be the first to share your thoughts.