Triacylglycerols are synthesized from fatty acyl CoAs and glycerol 3-phosphate.The glycolytic intermediate dihydroxyacetone phosphate is first reduces to glycerol 3-phosphate that is, in turn, acylated by glycerol-3- phosphate acyltransferase to make lysophosphatidic acid. This is then reacted with an additional acyl CoA molecule to form phosphatidic acid. Removal of the phosphate set from phosphatidic acid makes diacylglycerol (DAG) that is additional acylated with a third acyl CoA molecule to type triacylglycerol. ATP is not included in the biosynthesis of triacylglycerols. Alternatively the reactions are driven by the cleavage of the high-energy thioester bond between the acyl moiety and CoA. Both phosphatidic acid (phosphatidate) and DAG is also used as a second messenger in cell signaling and DAG is also used in the synthesis of membrane phospholipids.