Translocation of diacylglycerol kinase from the cytosol to the membrane in phorbol ester–treated Swiss 3T3 fibroblasts

Abstract

The tumor-promoting phorbol ester, 12-O-tetradecanoyl-phorbol-13-acetate, causes a rapid, partial redistribution of 1,2-diacylglycerol kinase from the cytosol to the particulate fraction of quiescent Swiss 3T3 fibroblasts. The inactive alpha form of the phorbol ester does not cause any change in diacylglycerol kinase localization, and depletion of protein kinase C by chronic administration of phorbol ester blocks the redistribution. Phorbol ester has no direct effect on membrane-bound diacylglycerol kinase in 3T3 cells. When phorbol ester is added to 3T3 membranes in the presence of ATP, Mg2+, and Ca2+, there is no activation of membrane-bound kinase, indicating that phorbol ester does not activate membrane-bound kinase through phosphorylation by protein kinase C. Stimulation of the cells with phorbol ester increases the total mass of diacylglycerol. In protein kinase C-depleted cells, addition of a cell-permeable synthetic diacylglycerol, dioctanoylglycerol, results in a partial redistribution of cytosolic diacylglycerol kinase to the membrane, also suggesting that the translocation of DAG kinase is regulated primarily by substrate concentration.