Specificities of acylglycerols and phospholipids for interaction with phorbol ester receptor on Friend leukemia cells.

Abstract

For the purpose of characterizing the nature of the phorbol ester receptor on intact cells, the effects of acylglycerols and phospholipids, which are known as activators of protein kinase C, on the binding of 3H-phorbol dibutyrate to Friend erythroid leukemia cells (FLC) were examined. Even when intact cells were used, diolein inhibited the binding of phorbol ester, and the degrees of inhibition by several kinds of acylglycerols paralleled their abilities to activate protein kinase C. On the other hand, phosphatidylserine enhanced the binding. Among phospholipids tested, the order of activities for increasing the binding was almost the same as that for activating protein kinase C. These results provide support for the hypothesis that the phorbol ester receptor in intact cells is protein kinase C, and that the ability of intact cells to bind phorbol ester is affected by endogenous lipids.