Catalyzes the conversion of phosphatidic acid (PA) to CDP-diacylglycerol (CDP-DAG), an essential intermediate in the synthesis of phosphatidylglycerol, cardiolipin and phosphatidylinositol (By similarity). Exhibits specificity for the nature of the acyl chains at the sn-1 and sn-2 positions in the substrate, PA and the preferred acyl chain composition is 1-stearoyl-2-arachidonoyl-sn-phosphatidic acid (By similarity). Plays an important role in regulating the growth and maturation of lipid droplets which are storage organelles at the center of lipid and energy homeostasis (PubMed:26946540). a 1,2-diacyl-sn-glycero-3-phosphate + CTP + H(+) = a CDP-1,2-diacyl-sn-glycerol + diphosphate 1-octadecanoyl-2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycero-3-phosphate + CTP + H(+) = 1-octadecanoyl-2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycero-3-cytidine-5'-diphosphate + diphosphate 1-octadecanoyl-2-(9Z,12Z-octadecadienoyl)-sn-glycero-3-phosphate + CTP + H(+) = 1-octadecanoyl-2-(9Z,12Z-octadecadienoyl)-sn-glycero-3-cytidine-5'-diphosphate + diphosphate 1-hexadecanoyl-2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycero-3-phosphate + CTP + H(+) = 1-hexadecanoyl-2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycero-3-cytidine-5'-diphosphate + diphosphate 1,2-di-(5Z,8Z,11Z,14Z)-eicosatetraenoyl-sn-glycero-3-phosphate + CTP + H(+) = 1,2-di-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycero-3-cytidine-5'-diphosphate + diphosphate 1-octadecanoyl-2-(9Z-octadecenoyl)-sn-glycero-3-phosphate + CTP + H(+) = 1-octadecanoyl-2-(9Z-octadecenoyl)-sn-glycero-3-cytidine-5'-diphosphate + diphosphate 1-octadecanoyl-2-(4Z,7Z,10Z,13Z,16Z,19Z-docosahexaenoyl)-sn-glycero-3-phosphate + CTP + H(+) = 1-octadecanoyl-2-(4Z,7Z,10Z,13Z,16Z,19Z-docosahexaenoyl)-sn-glycero-3-cytidine-5'-diphosphate + diphosphate 1,2-di-(9Z,12Z-octadecadienoyl)-sn-glycero-3-phosphate + CTP + H(+) = 1,2-di-(9Z,12Z-octadecadienoyl)-sn-glycero-3-cytidine-5'-diphosphate + diphosphate 1,2-di-(9Z-octadecenoyl)-sn-glycero-3-phosphate + CTP + H(+) = 1,2-di-(9Z-octadecenoyl)-sn-glycero-3-cytidine-5'-diphosphate + diphosphate Phospholipid metabolism; CDP-diacylglycerol biosynthesis; CDP-diacylglycerol from sn-glycerol 3-phosphate: step 3/3. Homodimer. Ubiquitous. Expressed in the ganglion cell layer and inner nuclear layer of the retina. Belongs to the CDS family.