Triacylglycerols (TAG) synthesis pathway require both DAG and
phosphatidate because of the following reason:
TAG synthesis is a multistep process and phosphatidic acid is a
key intermediate in triacylglycerol synthesis pathway. Phosphatidic
acid is produced by the acylation of glycerol-3-phosphate.
First step includes the hydrolysis of phosphatidate
diacylglycerol (DAG) by a specific phosphatase (Phosphatidate
phosphohydrolase).
Second step in triacylglycerols biosynthesis involves the
acylation of DAG intermediate to a triacylglycerol in a reaction
that is catalyzed by diglyceride acyltransferase.