CTP-dependent diacylglycerol kinase that catalyzes the phosphorylation of diacylglycerol (DAG) to phosphatidate (PA). Controls phosphatidate levels at the nuclear envelope. Counteracts the activity of PA phosphatase ned1. May be involved in vesicle trafficking between the endoplasmic reticulum and the Golgi apparatus (By similarity). Involved in pre-tRNA splicing (PubMed:11955632). a 1,2-diacyl-sn-glycerol + CTP = a 1,2-diacyl-sn-glycero-3-phosphate + CDP + H(+) Belongs to the DGK1 family.