Membrane localization of myocardial type II cyclic amp-dependent protein kinase activity

Larry R. Jones, Stephen W. Maddock, David R. Hathaway

Research output: Contribution to journalArticle

36 Scopus citations


Crude cardiac membrane vesicles were separated into subfractions of sarcolemma and sarcoplasmic reticulum. The subfractions were used to determine the origin and type of cyclic AMP-dependent protein kinase activity present in myocardial membranes. A cyclic AMP-binding protein of molecular weight 55 000 was covalently labeled with the photoaffinity probe 8-azido adenosine 3′,5′-mono[32P]phosphate, and found to copurify with the (Na+ + K+)-ATPase activity of sarcolemma, and away from the (Ca2+ + K+)-ATPase activity of sarcoplasmic reticulum. Endogenous cyclic AMP-dependent protein kinase activity also copurified with sarcolemma. Protein substrates phosphorylated by cyclic AMP-dependent protein kinase activity had apparent molecular weights of 21 000 and 8000 and were present in both sarcolemma and sarcoplasmic reticulum. However, while addition of cyclic AMP alone resulted in phosphorylation of sarcolemma proteins, both cyclic AMP and exogenous, soluble cyclic AMP-dependent kinase were required for phosphorylation of sarcoplasmic reticulum proteins. Addition of the calcium-binding protein, calmodulin, to either sarcolemma or sarcoplasmic reticulum resulted in phosphorylation of the 21 000 and 8000-dalton proteins, as well. The results suggest that cardiac sarcolemma contains an intrinsic type II cyclic AMP-dependent protein kinase activity that is not present in sarcoplasmic reticulum. On the other hand, Ca2+- and calmodulin-dependent protein kinase activity is present in both sarcolemma and sarcoplasmic reticulum.

Original languageEnglish (US)
Pages (from-to)242-253
Number of pages12
JournalBBA - Biomembranes
Issue number1
StatePublished - Feb 20 1981



  • (Myocardial membrane)
  • Calmodulin
  • cyclic AMP dependency
  • Localization
  • Protein kinase
  • Sarcolemma
  • Sarcoplasmic reticulum

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Cell Biology
  • Medicine(all)

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