PHOSPHORYLATION SITES OF PHOSPHOLIPASE C-GAMMA-1 BY PROTEIN-KINASE-C

Phosphoinositide-specific phospholipase C-gamma 1 is activated by phos phorylation of tyrosine residues by tyrosine kinase. The enzyme is als o phosphorylated by protein kinase C. In order to elucidate the regula tion mechanism of the enzyme action by protein kinase C the phosphoryl ation sites of phospholipase C-gamma 1 by the kinase have been identif ied. The identified sites were Ser(1227) in addition to Ser(1248) that have already been found. Phosphorylation patterns of phospholipase C- gamma 1 by protein kinase C wire all identical in vitro and in vivo. T he patterns were also identical although the sources of phospholipase C-gamma 1 were different-human, rat, and bovine.