Ca2+/calmodulin-dependent protein kinase II is phosphorylated by protein kinase C in vitro

Biochemistry. 1993 Mar 23;32(11):2923-30. doi: 10.1021/bi00062a024.


Protein kinase C (PKC) phosphorylated a synthetic peptide (CBP) that included the Thr-286 phosphorylation sequence and calmodulin binding domain of Ca2+/calmodulin-dependent protein kinase type II (CaM-kinase). Studies with a variety of truncated peptides suggested that the amino acid phosphorylated by PKC was Thr-286, the same amino acid that when autophosphorylated by Ca2+/calmodulin activation of CaM-kinase results in Ca2+/calmodulin-independent activity. These peptide studies also suggested that the C-terminal region of CBP is required to obtain maximal phosphorylation of Thr-286 by PKC. PKC also phosphorylated purified CaM-kinase from rat forebrain. Phosphopeptide analysis by one- and two-dimensional proteolytic maps of autophosphorylated CaM-kinase and CaM-kinase phosphorylated with PKC identified that there are both similar and unique sites phosphorylated. Phosphoamino acid analysis of CaM-kinase phosphorylated by PKC indicated that both Ser and Thr residues were phosphorylated. Even though Thr-286 of CaM-kinase appeared to be phosphorylated by PKC, no Ca2+/calmodulin-independent activity was detected, and, additionally, no significant change in Ca2+/CaM-dependent activation was detected. These results provide the first indication that these two important protein kinases may communicate directly through interenzyme phosphorylation.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Electrophoresis, Polyacrylamide Gel
  • Kinetics
  • Molecular Sequence Data
  • Peptide Fragments / isolation & purification
  • Peptides / chemical synthesis
  • Peptides / metabolism
  • Phosphopeptides / isolation & purification
  • Phosphorylation
  • Prosencephalon / enzymology*
  • Protein Kinase C / metabolism*
  • Protein Kinases / isolation & purification
  • Protein Kinases / metabolism*
  • Rats
  • Substrate Specificity


  • Peptide Fragments
  • Peptides
  • Phosphopeptides
  • Protein Kinases
  • Protein Kinase C
  • Calcium-Calmodulin-Dependent Protein Kinases