Protein kinase C activity in the spleen of trout (Salmo gairdneri) and the rectal gland of dogfish (Scyliorhinus canicula), and the effects of phosphatidylserine and diacylglycerol containing (n-3) polyunsaturated fatty acids.

1. High speed supernatant fractions of trout spleen and dogfish rectal gland contained 22.5 and 7.2 nmol/min/g tissue of protein kinase C activity respectively. 2. The effect of Ca2+ concentration on the activities with phosphatidylserine (PtdSer) alone, diacylglycerol (DAG) alone and PtdSer and DAG together were determined. Both enzymes required Ca2+ but activity was independent of Ca2+ concentration within the physiological range of 0.1-10 microns. 3. The effect of PtdSer and DAG containing (n - 3) polyunsaturated fatty acids (PUFA) on the activity of protein kinase C from both tissues was examined. Both enzymes were active with all lipids tested and showed little or no discrimination between lipids differing in their contents of (n-3) or (n-6) polyunsaturated fatty acids.