Distinct effects of saturated fatty acids on protein kinase C subspecies.

The effects of saturated fatty acids on the protein kinase C family were studied. Saturated fatty acids with carbon chain lengths of C12 to C14 activated the alpha-, beta-, gamma-, and epsilon-subspecies, and this activation was synergistic with that by diacylglycerol. Tridecanoic acid (C13) was most effective among the saturated fatty acids examined. Saturated fatty acids having carbon chain lengths of less than C10 were inert, and fatty acids with longer carbon chain lengths, such as C16 and C18, showed little effect. In contrast, fatty acids were almost inactive toward the delta-subspecies, and rather inhibited its activity in the presence of phosphatidylserine and diacylglycerol. Phorbol ester enhanced the activity of the alpha-, beta-, and gamma-subspecies when added with fatty acids; however, it suppressed the activity of the epsilon-subspecies in the presence of fatty acids. Saturated fatty acids having different effects on protein kinase C subspecies may be useful as tools for studying the mechanism and role of protein kinase C activation.