Stimulation of the type III olfactory adenylyl cyclase by calcium and calmodulin

Biochemistry. 1992 Jul 21;31(28):6492-8. doi: 10.1021/bi00143a019.


Characterization of adenylyl cyclases has been facilitated by the isolation of cDNA clones for distinct adenylyl cyclases including the type I and type III enzymes. Expression of type I adenylyl cyclase activity in animal cells has established that this enzyme is stimulated by calmodulin and Ca2+. Type III adenylyl cyclase is enriched in olfactory neurons and is regulated by stimulatory G proteins. The sensitivity of the type III adenylyl cyclase to Ca2+ and calmodulin has not been reported. In this study, type III adenylyl cyclase was expressed in human kidney 293 cells to determine if the enzyme is stimulated by Ca2+ and calmodulin. The type III enzyme was not stimulated by Ca2+ and calmodulin in the absence of other effectors. It was, however, stimulated by Ca2+ through calmodulin when the enzyme was concomitantly activated by either GppNHp or forskolin. The concentrations of free Ca2+ for half-maximal stimulation of type I and type III adenylyl cyclases were 0.05 and 5.0 microM Ca2+, respectively. These data suggest that the type III adenylyl cyclase is stimulated by Ca2+ when the enzyme is activated by G-protein-coupled receptors and that increases in free Ca2+ accompanying receptor activation may amplify the primary cyclic AMP signal.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenylyl Cyclases / classification
  • Adenylyl Cyclases / metabolism*
  • Calcium / pharmacology*
  • Calmodulin / pharmacology*
  • Cell Membrane / enzymology
  • Cells, Cultured
  • Cloning, Molecular
  • Colforsin / pharmacology
  • Enzyme Activation
  • Humans
  • In Vitro Techniques
  • Recombinant Proteins


  • Calmodulin
  • Recombinant Proteins
  • Colforsin
  • Adenylyl Cyclases
  • Calcium