Biosynthesis of CDP-DAG is catalyzed by phosphatidate cytidylyltransferase in the inner envelope membrane of plastids (for phosphatidylglycerol synthesis), in the inner mitochondrial membrane (for phosphatidylglycerol and diphosphatidylglycerol synthesis), and in the ER (for phosphatidylglycerol, phosphatidylinositol and phosphatidylserine synthesis).
Cardiolipin(CL) is synthesized in the inner mitochondrial membrane, when phosphatidylglycerol (PG) and cytidine diphosphate-diacylglycerol (CDP-DAG) are converted into CL. In addition to be synthesized in mitochondria, CDP-DAG may also be imported from ER to serve as the cardiolipin precursor pool. PGP (phosphatidylglycerol phosphate) catalyzes rate limiting step of cardiolipin biosynthesis.