Purification of the multifunctional calmodulin-dependent protein kinases from lung and liver, and the comparison to the brain enzyme.

We purified the multifunctional calmodulin-dependent protein kinases (calmodulin-kinase) from rat lung and rabbit liver, and compared the properties of this enzyme with those of the rat brain enzyme. The lung and liver enzymes had molecular weights (Mr's) of 530,000 and 330,000 with main subunits of 52 and 51 kDa, respectively. Although the lung and liver enzymes cross-reacted with antibodies to the brain enzyme, the immunoreactivity of the lung enzyme was weaker. The substrate specificity of the three enzymes showed differences in the relative reaction rate of phosphorylation. The patterns of phosphopeptides of the lung and liver enzymes were similar to each other and only partly common to that of the 60-kDa subunit of the brain enzyme.