Substrate specificity of diacylglycerol kinase-epsilon and the phosphatidylinositol cycle

We show that diacylglycerol kinase-epsilon (DGK epsilon) has less preference for the acyl chain at the sn-1 position of diacylglycerol (DAG) than the one at the sn-2 position. Although DGK epsilon discriminates between 1-stearoyl-2-arachidonoyl-DAG and 1-palmitoyl-2-arachidonoyl-DAG, it has similar substrate preference for 1-stearoyl-2-arachidonoyl-DAG and 1,2-diarachidonoyl-DAG. We suggest that in addition to binding to the enzyme, the acyl chain at the sn-1 position may contribute to the depth of insertion of the DAG into the membrane. Thus, the DAG intermediate of the PI-cycle, 1-stearoyl-2-arachidonoyl-DAG, is not the only DAG that is a good substrate for DGKe, the DGK isoform involved in PI-cycling. (C) 2011 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.