Phosphatidate cytidylyltransferase (EC 2.7.7.41)^[1][2][3] (also known as CDP- diacylglycerol synthase) (CDS) is the enzyme that catalyzes the synthesis of CDP-diacylglycerol from cytidine triphosphate and phosphatidate.

CTP + phosphatidate ${\displaystyle \rightleftharpoons }$ diphosphate + CDP-diacylglycerol

Thus, the two substrates of this enzyme are cytidine triphosphate, or CTP, and phosphatidate, whereas its two products are diphosphate and CDP-diacylglycerol.

CDP-diacylglycerol is an important branch point intermediate in both prokaryotic and eukaryotic organisms. CDS is a membrane-bound enzyme.

This enzyme belongs to the family of transferases, specifically those transferring phosphorus-containing nucleotide groups (nucleotidyltransferases). The systematic name of this enzyme class is CTP:phosphatidate cytidylyltransferase. Other names in common use include CDP diglyceride pyrophosphorylase, CDP-diacylglycerol synthase, CDP-diacylglyceride synthetase, cytidine diphosphoglyceride pyrophosphorylase, phosphatidate cytidyltransferase, phosphatidic acid cytidylyltransferase, CTP:1,2-diacylglycerophosphate-cytidyl transferase, CTP-diacylglycerol synthetase, DAG synthetase, and CDP-DG. This enzyme participates in glycerophospholipid metabolism and phosphatidylinositol signaling system.