Diacylglycerol kinase that converts diacylglycerol/DAG into phosphatidic acid/phosphatidate/PA and regulates the respective levels of these two bioactive lipids (PubMed:26748701). 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:26748701). Within the adrenocorticotropic hormone signaling pathway, produces phosphatidic acid which in turn activates NR5A1 and subsequent steroidogenic gene transcription (By similarity). Also functions downstream of the nerve growth factor signaling pathway being specifically activated in the nucleus by the growth factor (By similarity). Through its diacylglycerol activity also regulates synaptic vesicle endocytosis (PubMed:26748701). a 1,2-diacyl-sn-glycerol + ATP = a 1,2-diacyl-sn-glycero-3-phosphate + ADP + H(+) 1,2-di-(9Z-octadecenoyl)-sn-glycerol + ATP = 1,2-di-(9Z-octadecenoyl)-sn-glycero-3-phosphate + ADP + H(+) 1-O-hexadecyl-sn-glycerol + ATP = 1-O-hexadecyl-sn-glycero-3-phosphate + ADP + H(+) 1-O-hexadecyl-2-acetyl-sn-glycerol + ATP = 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphate + ADP + H(+) 1-octadecanoyl-2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycerol + ATP = 1-octadecanoyl-2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycero-3-phosphate + ADP + H(+) Activated by phosphatidylserine. Lipid metabolism; glycerolipid metabolism. Interacts with RHOA (constitutively activated, GTP-bound); the interaction inhibits DGKQ. Interacts with PRKCE. Interacts with PRKCH. Interacts with PLCB1. Interacts with NR5A1; the interaction requires both LXXLL motifs in DGKQ and is required for full phosphatidic acid-mediated activation of NR5A1. Translocates to the plasma membrane in response to steroid hormone receptor stimulation. Translocation to the plasma membrane is dependent on G-protein coupled receptor stimulation and subsequent activation of PRKCE and probably PRKCH. Translocates to the nucleus in response to thrombin stimulation (By similarity). Association with the nuclear matrix is regulated by nerve growth factor (By similarity). Widely expressed in all brain regions, including the cortex and hippocampus with a specific expression in neuronal cells (at protein level). Expression increases through development and peaks at postnatal day 14. The L-X-X-L-L repeats are both required for binding and phosphatidic acid-mediated activation of the nuclear receptor NR5A1. Phosphorylated by PRKCE and PRKCH in vitro. Homozygous knockout mice display no overt phenotype with respect to body size, mating, and lifespan. Belongs to the eukaryotic diacylglycerol kinase family.