Ca2+ inhibition of type III adenylyl cyclase in vivo

G. A. Wayman, S. Impey, D. R. Storm

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126 Scopus citations


Type III adenylyl cyclase is stimulated by β-adrenergic agonists and glucagon in vitro and in vivo, but not by Ca2+ and calmodulin. However, the enzyme is stimulated by Ca2+ and calmodulin in vitro when it is concomitantly activated by the guanyl nucleotide stimulatory protein G(s) (Choi, E. J., Xia, Z., and Storm, D. R. (1992a) Biochemistry 31, 6492-6498). Here, we examined regulation of type III adenylyl cyclase by G(s)-coupled receptors and intracellular Ca2+ in vivo. Surprisingly, intracellular Ca2+ inhibited hormone-stimulated type III adenylyl cyclase activity. Submicromolar concentrations of intracellular free Ca2+, which stimulated type I adenylyl cyclase, inhibited glucagon- or isoproterenol-stimulated type III adenylyl cyclase. Inhibition of type III adenylyl cyclase by intracellular Ca2+ was not mediated by G(i), cAMP-dependent protein kinase, or protein kinase C. However, an inhibitor of CaM kinases antagonized Ca2+ inhibition of the enzyme, and coexpression of constitutively activated CaM kinase II completely inhibited isoproterenol-stimulated type III adenylyl cyclase activity. We propose that Ca2+ inhibition of type III adenylyl cyclase may serve as a regulatory mechanism to attenuate hormone-stimulated cAMP levels in some tissues.

Original languageEnglish (US)
Pages (from-to)21480-21486
Number of pages7
JournalJournal of Biological Chemistry
Issue number37
StatePublished - 1995
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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