Phosphorylation of the calmodulin-dependent protein phosphatase by protein kinase C

The calmodulin-dependent protein phosphatase was shown to be phosphorylated by the Ca2+, phospholipid-dependent protein kinase (protein kinase C). Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the 61 kDa catalytic subunit was phosphorylated. Phosphorylation by protein kinase C was stimulated up to 15-fold by addition of phosphatidyl-L-serine and between 0.5 to 1.0 mole of phosphate was incorporated per mole of phosphatase. It is possible that protein kinase C is involved in the regulation of the calmodulin-dependent protein phosphatase via this novel phosphorylation of the enzyme.