Catalyzes the initial step in triglyceride hydrolysis in adipocyte and non-adipocyte lipid droplets (PubMed:15550674, PubMed:23066022, PubMed:15337759, PubMed:16150821, PubMed:16679289, PubMed:17074755, PubMed:16675698, PubMed:17114792). Exhibits a strong preference for the hydrolysis of long-chain fatty acid esters at the sn-2 position of the glycerol backbone and acts coordinately with LIPE/HLS and DGAT2 within the lipolytic cascade (PubMed:23066022). Also possesses acylglycerol transacylase and phospholipase A2 activities (By similarity). Transfers fatty acid from triglyceride to retinol, hydrolyzes retinylesters, and generates 1,3-diacylglycerol from triglycerides (By similarity). Regulates adiposome size and may be involved in the degradation of adiposomes (By similarity). May play an important role in energy homeostasis (PubMed:16675698). May play a role in the response of the organism to starvation, enhancing hydrolysis of triglycerides and providing free fatty acids to other tissues to be oxidized in situations of energy depletion (PubMed:15337759). a triacylglycerol + H2O = a diacylglycerol + a fatty acid + H(+) a triacyl-sn-glycerol + H2O = a 1,2-diacylglycerol + a fatty acid + H(+) a triacyl-sn-glycerol + H2O = a 2,3-diacyl-sn-glycerol + a fatty acid + H(+) a triacyl-sn-glycerol + H2O = 1,3-diacyl-sn-glycerol + a fatty acid + H(+) 1,2,3-tri-(9Z-octadecenoyl)-glycerol + H2O = (9Z)-octadecenoate + 1,3-di-(9Z-octadecenoyl)-glycerol + H(+) 1,2,3-tri-(9Z)-hexadecenoylglycerol + H2O = (9Z)-hexadecenoate + 1,3-di-(9Z)-hexadecenoylglycerol + H(+) 1,2,3-tri-(9Z,12Z)-octadecadienoylglycerol + H2O = (9Z,12Z)-octadecadienoate + 1,3-di-(9Z,12Z)-octadecadienoylglycerol + H(+) 1,2,3-tri-(9Z,12Z,15Z)-octadecatrienoylglycerol + H2O = (9Z,12Z,15Z)-octadecatrienoate + 1,3-di-(9Z,12Z,15Z)-octadecatrienoylglycerol + H(+) 1,3-di-(9Z)-octadecenoyl-2-hexadecanoylglycerol + H2O = 1,3-di-(9Z-octadecenoyl)-glycerol + H(+) + hexadecanoate 1,2-di-(9Z)-octadecenoyl-3-hexadecanoyl-sn-glycerol + H2O = (9Z)-octadecenoate + 1-(9Z)-octadecenoyl-3-hexadecanoyl-sn-glycerol + H(+) 1-hexadecanoyl-2,3-di-(9Z)-octadecenoyl-sn-glycerol + H2O = (9Z)-octadecenoate + 1-hexadecanoyl-3-(9Z)-octadecenoyl-sn-glycerol + H(+) 1,2,3-tri-(9Z-octadecenoyl)-glycerol + H2O = (9Z)-octadecenoate + 2,3-di-(9Z)-octadecenoyl-sn-glycerol + H(+) 1,2,3-tri-(9Z)-hexadecenoylglycerol + H2O = (9Z)-hexadecenoate + 2,3-di-(9Z)-hexadecenoyl-sn-glycerol + H(+) 1,2,3-tri-(9Z,12Z)-octadecadienoylglycerol + H2O = (9Z,12Z)-octadecadienoate + 2,3-di-(9Z,12Z)-octadecadienoyl-sn-glycerol + H(+) 1,2,3-tri-(9Z,12Z,15Z)-octadecatrienoylglycerol + H2O = (9Z,12Z,15Z)-octadecatrienoate + 2,3-di-(9Z,12Z,15Z)-octadecatrienoyl-sn-glycerol + H(+) 1,3-di-(9Z)-octadecenoyl-2-hexadecanoylglycerol + H2O = (9Z)-octadecenoate + 2-hexadecanoyl-3-(9Z)-octadecenoyl-sn-glycerol + H(+) 1-hexadecanoyl-2,3-di-(9Z)-octadecenoyl-sn-glycerol + H2O = 2,3-di-(9Z)-octadecenoyl-sn-glycerol + H(+) + hexadecanoate 1,2-di-(9Z)-octadecenoyl-3-hexadecanoyl-sn-glycerol + H2O = (9Z)-octadecenoate + 2-(9Z-octadecenoyl)-3-hexadecanoyl-sn-glycerol + H(+) (9Z)-octadecenoate + 1,2-di-(9Z-octadecenoyl)-glycerol + H(+) = 1,2,3-tri-(9Z-octadecenoyl)-glycerol + H2O a 1,3-diacylglycerol + a 1-acylglycerol = a triacylglycerol + glycerol a 1,2-diacylglycerol + a 1-acylglycerol = a triacylglycerol + glycerol 2 a 1-acylglycerol = a 1,2-diacylglycerol + glycerol a triacyl-sn-glycerol + all-trans-retinol = a diacylglycerol + an all-trans-retinyl ester 1,3-di-(9Z-octadecenoyl)-glycerol + 1-(9Z-octadecenoyl)-glycerol = 1,2,3-tri-(9Z-octadecenoyl)-glycerol + glycerol 1,2-di-(9Z-octadecenoyl)-glycerol + 1-(9Z-octadecenoyl)-glycerol = 1,2,3-tri-(9Z-octadecenoyl)-glycerol + glycerol 2 1-(9Z-octadecenoyl)-glycerol = 1,2-di-(9Z-octadecenoyl)-glycerol + glycerol 1,2,3-tri-(9Z-octadecenoyl)-glycerol + all-trans-retinol = all-trans-retinyl 9Z-octadecenoate + di-(9Z)-octadecenoylglycerol a 1,2-diacyl-sn-glycero-3-phosphocholine + H2O = a 1-acyl-sn-glycero-3-phosphocholine + a fatty acid + H(+) Stimulated by PKA-dependent PLIN phosphorylation. Glycerolipid metabolism; triacylglycerol degradation. Interacts with ABHD5; this association stimulates PNPLA2 triglyceride hydrolase activity (PubMed:16679289, PubMed:17189257). Interacts with SERPINF1; this interaction stimulates the phospholipase A2 activity of PNPLA2 (By similarity). Despite a colocalization in lipid droplets, it probably does not interact with PLIN (PubMed:17189257). Interacts with PLIN5; prevents interaction with ABHD5 (PubMed:21148142, PubMed:21393244). Interacts with FAF2 (By similarity). Expressed at high levels in white and brown adipose tissue, and to a lesser degree in testis and cardiac muscle. Barely detected in liver, spleen, thymus, kidney, skeletal muscle, and brain. Among the white adipose depots, gonadal fat showed the highest level of expression compared with inguinal and renal white adipose tissues. Increased expression when preadipocytes are induced to differentiate to adipocytes. Not detected in proliferating or confluent preadipocytes. Transiently induced during fasting. cAMP and glucagon may not be involved in the induction during fasting. Induced by dexamethasone. Down-regulated by insulin, isoprotenerol and TNF-alfa. Expression is not affected by glucose and by growth hormone. Expression is reduced in fasted leptin deficient mouse (ob/ob), an obese mouse model. Expression is not affected in fed ob/ob mouse. Phosphorylation at Ser-406 by PKA is increased during fasting and moderate intensity exercise, and moderately increases lipolytic activity. Mice show increased adipose mass and triacylglycerol deposition in multiple tissues. They accumulate large amounts of lipid in the heart, causing cardiac dysfunction and premature death.