Identification and characterization of delta B-CaM kinase and delta C-CaM kinase from rat heart, two new multifunctional Ca2+/calmodulin-dependent protein kinase isoforms

Biochim Biophys Acta. 1994 Mar 10;1221(1):89-101. doi: 10.1016/0167-4889(94)90221-6.


We have identified, expressed and characterized two new isoforms of the multifunctional Ca2+/calmodulin-dependent kinase (CaM kinase) cloned from rat heart. Both isoforms are variants of the neuronal delta-CaM kinase (termed delta A-CaM kinase), and are designated as delta B-CaM kinase and delta C-CaM kinase. The new isoforms differ from delta A-CaM kinase in its isoform-specific insert region, between nucleotides 984 to 1087 of the delta A-CaM kinase cDNA. Replacing these 102 nucleotides, a sequence of 33 nucleotides which code for 11 amino acids (KRKSSSSQMM) are introduced in delta B-CaM kinase. The delta C-CaM kinase lacks all 102 nucleotides and the corresponding 34 amino acids which they encode. The predicted molecular masses of the delta B- and delta C-CaM kinase isoforms are 57,697 Da and 56,446 Da, respectively. Recombinant delta-CaM kinases purified from transfected COS-7 cells were found to associate into a larger holoenzyme estimated to contain 8 to 10 subunits. The relative subunit molecular masses on SDS-polyacrylamide gel electrophoresis are 59 kDa, 54 kDa and 52 kDa for delta A-, delta B- and delta C-CaM kinase, respectively. All three isoforms showed a strict dependence on Ca2+/calmodulin for activity and exhibited the Ca(2+)-dependent autophosphorylation and resultant conversion to Ca(2+)-independent kinase activity, characteristic features of multifunctional CaM kinase. Phosphopeptide analysis after partial CNBr digestion suggests that delta B-CaM kinase is the predominant soluble CaM kinase species purified from rat heart.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Calcium-Calmodulin-Dependent Protein Kinases / biosynthesis
  • Calcium-Calmodulin-Dependent Protein Kinases / isolation & purification
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
  • Calmodulin / pharmacology
  • Cell Line
  • Cloning, Molecular
  • DNA Primers
  • Electrophoresis, Polyacrylamide Gel
  • Enzyme Activation
  • Genetic Variation
  • Isoenzymes / biosynthesis
  • Isoenzymes / isolation & purification
  • Isoenzymes / metabolism*
  • Kinetics
  • Macromolecular Substances
  • Molecular Sequence Data
  • Molecular Weight
  • Mutagenesis, Site-Directed
  • Myocardium / enzymology*
  • Phosphopeptides / isolation & purification
  • Phosphorylation
  • Polymerase Chain Reaction
  • Rats
  • Sequence Homology, Amino Acid
  • Transfection


  • Calmodulin
  • DNA Primers
  • Isoenzymes
  • Macromolecular Substances
  • Phosphopeptides
  • Calcium-Calmodulin-Dependent Protein Kinases

Associated data

  • GENBANK/S69668
  • GENBANK/S69671
  • GENBANK/S69672