Identification of Phorbol Myristate Acetate Stimulated Kinase in Zea mays

Following DEAE-Sephacel and affinity chromatography a highly enriched lipid stimulated kinase activity could be recovered with a purification fold of 1725. The peak kinase activity fraction eluted with 0.1 mM calcium from phosphatidyl serine affinity chromatography showed a major protein of 70 kD and a minor band of 55 kD molecular weight and showed kinase activity that was stimulated by phorbol myristate acetate in the presence of phosphatidylserine and calcium. The optimum requirement was 2.5 × 10⁻⁶ M, 1.25 × 10⁻⁴ M, 1 × 10⁻⁴ M, and 1.7 × 10⁻⁶ M for phorbol myristate acetate, phosphatidyl serine, oleyl acetyl glycerol and free calcium respectively. The kinase activity was inhibited by H-7 and staurosporine. The binding of [³H]-phorbol myristate acetate was associated with purified fraction as resolved by gel electrophoresis and the kinase activity was also precipitated by animal protein kinase C antibodies. The present data give strong evidence for the presence of phorbol myristate acetate stimulated kinase in plants.