Mg(2+)-dependent phosphatidate (PA) phosphatase which catalyzes the dephosphorylation of PA to yield diacylglycerol (PubMed:16467296, PubMed:16968695, PubMed:17910939, PubMed:17971454, PubMed:20876142, PubMed:21081492, PubMed:29765047). Required for de novo lipid synthesis and formation of lipid droplets (PubMed:21422231). Controls transcription of phospholipid biosynthetic genes and nuclear structure by regulating the amount of membrane present at the nuclear envelope (PubMed:15889145). Involved in plasmid maintenance, in respiration and in cell proliferation (PubMed:8437575). a 1,2-diacyl-sn-glycero-3-phosphate + H2O = a 1,2-diacyl-sn-glycerol + phosphate Phenylglyoxal and propranolol inhibit activity in dose-dependent manners with IC(50) values of 1.3 mM and 0.2 mM, respectively. The N-terminal amphipathic helix (residues 1 to 18) is involved in the membrane recruitment. Contains one Asp-Xaa-Asp-Xaa-Thr (DXDXT) motif, a catalytic motif essential for phosphatidate phosphatase activity. Acetylation at Lys-496 and Lys-801 by ESA1 promotes synthesis of diacylglycerol. Phosphorylated by CDC28 at the onset of mitosis, and dephosphorylated by the NEM1-SPO7 complex. Phosphorylation regulates recruitment on promoters of lipid biosynthetic enzymes. Present with 3910 molecules/cell in log phase SD medium. Belongs to the lipin family.