Update on glycerol-3-phosphate acyltransferases: the roles in the development of insulin resistance

Glycerol-3-phosphate acyltransferase 1 (GPAT1) and GPAT2 are localized in the mitochondrial outer membrane, while GPAT3, GPAT4, phosphatidic acid phosphatase (PAP/lipin), and diacylglycerol acyltransferase (DGAT) are localized in the endoplasmic reticulum (ER) membrane. In addition, 1-acyl glycerol-3-phosphate acyltransferase (AGPAT) is localized in both the mitochondrial outer membrane and the endoplasmic reticulum (ER) membrane. GPATs competitively catalyze acyl-CoA and glycerol-3-phosphate (G3P) to produce lysophosphatidic acid (LPA) and protect acyl-CoA from β-oxidation. Then, LPA and acyl-CoA are converted to phosphatidic acid (PA) by AGPAT. Consequently, PA is dephosphorylated by lipin to diacylglycerols (DAG). DAG and acyl-CoA are catalyzed by DGAT to form triacylglycerol (TAG). Furthermore, TAG synthesizes lipid droplets (LD). The intermediate products (LPA, PA, DAG) are responsible for intercellular signal transductio