Calmodulin-dependent protein kinases purified from rat brain and rabbit liver

Charles M. Schworer, Robert W. McClure, Thomas R. Soderling

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


A calmodulin-dependent protein kinase was purified from rat brain by the same protocol used previously for a rabbit liver calmodulin-dependent glycogen synthase kinase. The rat brain kinase readily phosphorylated rabbit skeletal muscle glycogen synthase at sites 1b and 2, the same sites phosphorylated by rabbit liver calmodulin-dependent kinase. The two kinases have other similarities: substrate specificity, potent inhibition by sodium fluoride, and nearly equal Ka's (10-20 nm) for calmodulin. Also, both enzymes have similar Stokes radii, 70 Å (rabbit liver) and 75 Å (rat brain), but quite different sedimentation coefficients, 10.6 S and 17.4 S, respectively. Consequently, the calculated molecular weights are also different: 560,000 for the brain enzyme and 300,000 for the liver enzyme. The major subunit of the rat brain kinase appears to be a single 51-kDa peptide, not a doublet pattern of 51- and 53-kDa subunits that is characteristic of the rabbit liver enzyme. Our findings are consistent with the hypothesis that the rat brain and rabbit liver enzymes belong to a class of closely related calmodulin-dependent protein kinases, possibly isozymes. This class of enzymes may be responsible for regulating several of the known calcium-dependent physiological functions.

Original languageEnglish (US)
Pages (from-to)137-145
Number of pages9
JournalArchives of Biochemistry and Biophysics
Issue number1
StatePublished - Oct 1985
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology


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