Plays important roles in controlling the metabolism of fatty acids at differents levels. Acts as a magnesium-dependent phosphatidate phosphatase enzyme which catalyzes the conversion of phosphatidic acid to diacylglycerol during triglyceride, phosphatidylcholine and phosphatidylethanolamine biosynthesis in the reticulum endoplasmic membrane. Acts also as a nuclear transcriptional coactivator for PPARGC1A/PPARA to modulate lipid metabolism gene expression. Is involved in adipocyte differentiation. May also be involved in mitochondrial fission by converting phosphatidic acid to diacylglycerol. Interacts (via LXXIL motif) with PPARA. Interacts with PPARGC1A. Interaction with PPARA and PPARGC1A leads to the formation of a complex that modulates gene transcription. Interacts with MEF2C. Specifically expressed in skeletal muscle. Also abundant in adipose tissue. Lower levels in some portions of the digestive tract. Inhibited by N-ethylmaleimide. Belongs to the lipin family. Note: This description may include information from UniProtKB.