Molecular cloning of the cDNA encoding the third polypeptide (γ) of brain calmodulin-dependent protein kinase II

cDNA clones for three distinct types of rat brain calmodulin-dependent protein kinase II have been isolated. Two of them were identified as cDNA clones for the α and β subunits of this kinase. The other showed a nucleotide sequence similar but, not identical, to that encoding either the α or β subunit. The cDNA sequence encoded a polypeptide, designated γ, consisting of 527 amino acid residues with a molecular weight of 59,038. The deduced amino acid sequence of γ was 84 and 87% homologous to those of α and β, respectively. Higher homologies of the sequences were found in the amino-terminal halves of the three species, α, β, and γ. RNA blot analysis revealed that the mRNAs for α, β, and γ were expressed in rat brain with different regional specificities.