Diacylglycerol kinase that converts diacylglycerol/DAG into phosphatidic acid/phosphatidate/PA and regulates the respective levels of these two bioactive lipids (PubMed:11309392, PubMed:22627129, PubMed:9099683). 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:11309392, PubMed:17664281, PubMed:26748701). Within the adrenocorticotropic hormone signaling pathway, produces phosphatidic acid which in turn activates NR5A1 and subsequent steroidogenic gene transcription (PubMed:17664281). 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). {ECO:0000250|UniProtKB:D3ZEY4, ECO:0000269|PubMed:11309392, ECO:0000269|PubMed:17664281, ECO:0000269|PubMed:22627129, ECO:0000269|PubMed:26748701, ECO:0000269|PubMed:9099683}. This is the function of DGKQ (diacylglycerol kinase theta, Ensembl gene identifier ENSG00000145214).