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 language | English |
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Pages (from-to) | 28-35 |
Number of pages | 8 |
Journal | Archives of Biochemistry and Biophysics |
Volume | 241 |
Issue number | 1 |
DOIs | |
State | Published - 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.
Funders | Funder number |
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American Heart Association Kentucky Affiliate |
ASJC Scopus subject areas
- Biophysics
- Biochemistry
- Molecular Biology