ACYL-CHAIN DEPENDENCE OF DIACYLGLYCEROL ACTIVATION OF PROTEIN-KINASE-C ACTIVITY IN-VITRO

Stimulation of protein kinase C (PKC) activity in lipid vesicles in vi tro was achieved by pure molecular species of diacylglycerol (DAG), sp ecifically 1-stearoyl-2-acyl-sn-glycerol substituted with 2-arachidono yl, 2-eicosapentaenoyl or 2-docosahexaenoyl (SAG, SEG, and SDG, respec tively). PKC activity was measured in lipid vesicles containing 30 mol % -palmitoyl-2-oleoyl-sn-glycerol-3-phospho-L-serine (POPS), 68-70 mol % 1-palmitoyl-2-oleoyl-sn-glycerol-3-phosp (POPC), and 0-2 mol% DAG in the presence of 20 mu M calcium. Our results demonstrate that amplifi cation of PKC activity differs significantly among these molecular spe cies of DAG. in particular, SDG at 0.5 mol% is more potent in increasi ng PKC activity than is dioleoylglycerol (DOG), SEG, or SAG, and SAG a nd SDG at 1.0 and 2.0 mol% have similar potencies which are greater th an those of DOG or SEG. These findings demonstrate that sn-2 substitut ions in DAG by specific n-3 and n-6 polyunsaturated fatty acids increa se the potency of DAG to stimulate PKC activity in vitro. (C) 1996 Aca demic Press, Inc.