Sequence of the sites phosphorylated by protein kinase C in the smooth muscle myosin light chain.

摘要: We have determined the sequence of sites phosphorylated by protein kinase C in turkey gizzard smooth muscle myosin light chain. In contrast to previous work (Nishikawa, M., Hidaka, H., and Adelstein, R. S. (1983) J. Biol. Chem. 258, 14069-14072), two-dimensional tryptic peptide maps both heavy meromyosin isolated chain showed two major phosphopeptides, one containing phosphoserine other phosphothreonine. purified succinylated phosphopeptides using reverse phase DEAE high pressure liquid chromatography. The serine-containing peptide, residues 1-4 (Ac-SSKR), is NH2-terminal peptide. serine residue may be either 1 or 2. threonine-containing 5-16, yielded AKAKTTKKRPQR. Analysis yields radioactivity products from automated Edman degradation that threonine 9 phosphorylation site.