Phosphorylation of myosin light chain in intact pig leukocytes stimulated by phorbol 12-myristate 13-acetate.

Phosphorylation of myosin light chain was investigated in intact pig polymorphonuclear leukocytes. The labeling of the myosin light chain (Mr = 21000) was increased by exposure of the cells to phorbol 12-myristate 13-acetate. Two-dimensional gel electrophoresis revealed three forms of Mr = 21000 light chain, of which two were phosphorylated. The phosphorylation of the myosin light chain was inhibited by neither N-(6-aminohexyl)-5-chloro-1-naphthalene sufonamide nor trifluoperazine, suggesting that calmodulin is not involved in the phosphorylation.