Effects of the fatty acid composition of phosphatidylserine and diacylglycerol on the in vitro activity of protein kinase C from rat spleen: influences of (n-3) and (n-6) polyunsaturated fatty acids.

Protein kinase C from rat spleen was assayed with different phosphatidylserines (PtdSer) and diacylglycerols (DAG): PtdSer from bovine brain containing 0.8% 20:4 (n-6), 1.0% 20:5 (n-3) and 5.7% 22:6 (n-3); PtdSer from trout liver lacking 20:4 (n-6) and containing 0.6% 20:5 (n-3) and 43% 22:6 (n-3); 1-stearoyl-2-arachidonylglycerol prepared from synthetic 1-stearoyl-2-arachidonyl-sn-glycero-3-phosphocholine; DAG, prepared from cod roe phospholipids, containing 2.1% 20:4 (n-6), 11.7% 20:5 (n-3) and 29.0% 22:6 (n-3); 1,2-dioleoylglycerol. When assayed with Ca2+ in the absence of DAG there was no difference in the activity of protein kinase C between the two PtdSer. When assayed with Ca2+ in the absence of PtdSer the (n-6)-rich DAG was 2 fold more active, and the (n-3)-rich DAG 1.3 fold more active than 1,2-dioleoylglycerol. When assayed in the presence of both PtdSer and DAG, the enzyme was equally active with all of the DAG, but was 1.3 fold more active with the PtdSer from bovine brain than with the PtdSer from trout liver.