Multiple isoforms catalyze each step in the glycerol-3-phosphate pathway of TAG synthesis

Multiple isoforms catalyze each step in the glycerol-3-phosphate pathway of TAG synthesis. GPAT1 and GPAT2 on the outer mitochondrial membrane compete with carnitine palmitoyl transferase-1 for acyl-CoAs that may be used for glycerolipid biosynthesis or for β-oxidation. Like GPAT1 and 2, GPAT3 and GPAT4 catalyze the esterification of glycerol-3-phosphate to form lysophosphatidic acid (LPA). As many as 5 possible 1-acyl-sn-glycerol-3-phosphate acyltransferases (AGPAT; also known as LPAAT) esterify LPA to form phosphatidic acid (PA). Three isoforms of phosphatidic acid phosphohydrolase (PAPase, which is also known as lipin), hydrolyze the phosphate to form diacylglycerol (DAG). Two major isoforms of diacylglycerol acyltransferase (DGAT) catalyze the third esterification to form triacylglycerol (TAG). Both PA and DAG are also precursors for the glycerophospholipids, phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI), phosphatidylglycerol (PG), and cardiolipin (CL). The DAG produced by this pathway can activate protein kinase C.

Publication

Glycerol-3-phosphate acyltransferases: Rate limiting enzymes of triacylglycerol biosynthesis. () Angela A. Wendel, et al. Biochim Biophys Acta. ;1791(6):501-506. Figure: F2. Homo sapiens

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