Ca2+-dependent inhibition of smooth muscle adenylate cyclase activity

Michael T. Piascik, Bradford Addison, Michael Babich

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

We have examined the inhibitory regulation by Ca2+ of the adenylate cyclase activity associated with microsomes isolated from bovine aorta smooth muscle. In the presence of 2 mm MgCl2, Ca2+ (0.8-100 μm) inhibited in a noncompetitive manner activation of the enzyme by GTP, Gpp[NH]p, or forskolin. In all instances the value for half-maximal inhibition was between 2 and 3 μm. In contrast, Ca2+ inhibited the activation by MgCl2 (2-50 mm), alone or in the presence of GTP, in a competitive manner. The inhibition of adenylate cyclase by 10 μm Ca2+ was reversed in the presence of either 5 or 25 μm calmodulin or troponin C. These data show that (i) Ca2+, at concentrations similar to those which activate smooth muscle contraction, inhibits the stimulation of adenylate cyclase by several activators; (ii) Ca2+ and Mg2+ compete for a common site on the smooth muscle adenylate cyclase complex; and (iii) the reversal of Ca2+-dependent inhibition by Ca2+-binding proteins may be produced by chelation of the metal by these proteins.

Original languageEnglish
Pages (from-to)28-35
Number of pages8
JournalArchives of Biochemistry and Biophysics
Volume241
Issue number1
DOIs
StatePublished - Aug 15 1985

Bibliographical note

Funding Information:
This work was supported in part by funds from the American Heart Association-Kentucky Affiliate. We thank Deborah Turner for the supervision the preparation of this manuscript and Susan Farmer for excellent technical assistance.

Funding

This work was supported in part by funds from the American Heart Association-Kentucky Affiliate. We thank Deborah Turner for the supervision the preparation of this manuscript and Susan Farmer for excellent technical assistance.

FundersFunder number
American Heart Association Kentucky Affiliate

    ASJC Scopus subject areas

    • Biophysics
    • Biochemistry
    • Molecular Biology

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