Membrane-bound diacylglycerol kinase that converts diacylglycerol/DAG into phosphatidic acid/phosphatidate/PA and regulates the respective levels of these two bioactive lipids (PubMed:15544348, PubMed:19744926, PubMed:21477596, PubMed:22108654, PubMed:23949095). Thereby, acts as a central switch between the signaling pathways activated by these second messengers with different cellular targets and opposite effects in numerous biological processes (PubMed:15544348, PubMed:8626589). Also plays an important role in the biosynthesis of complex lipids (PubMed:8626589). Displays specificity for diacylglycerol substrates with an arachidonoyl acyl chain at the sn-2 position, with the highest activity toward 1-octadecanoyl-2- (5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycerol the main diacylglycerol intermediate within the phosphatidylinositol turnover cycle (PubMed:19744926, PubMed:22108654, PubMed:23274426). Can also phosphorylate diacylglycerol substrates with a linoleoyl acyl chain at the sn-2 position but much less efficiently (PubMed:22108654). {ECO:0000269|PubMed:15544348, ECO:0000269|PubMed:19744926, ECO:0000269|PubMed:21477596, ECO:0000269|PubMed:22108654, ECO:0000269|PubMed:23274426, ECO:0000269|PubMed:23949095, ECO:0000303|PubMed:15544348, ECO:0000303|PubMed:8626589}. This is the function of ENSG00000153933 (DGKE, diacylglycerol kinase epsilon).