PURIFICATION AND CHARACTERIZATION OF PROTEIN-KINASE-C FROM A HIGHER-PLANT, BRASSICA-CAMPESTRIS L

Protein kinase C (PKC) was partially purified from Brassica campestris L., by successive chromatographies on DEAE-cellulose membrane, hydrox yapatite and phenyl-5PW columns. The purified preparation showed typic al characteristics of the conventional type of mammalian PKC that resp onds to Ca2+, phosphatidylserine, and diacylglycerol or the tumor-prom oting phorbol ester, phorbol 12-myristate 13-acetate. The plant PKC ac tivity was apparently associated with a 75-kDa polypeptide that was re cognized by an antibody against the catalytic domain of rat PKC. Subst rate specificity of the plant PKC was similar to that of the rat PKC. A synthetic peptide corresponding to residues 4-14 of myelin basic pro tein, which is a selective substrate for the mammalian PKC, was phosph orylated efficiently by the plant PKC. These results indicate the exis tence of a PKC equivalent in higher plant cells. (C) 1994 Academic Pre ss, Inc.