Catalyzes the final step in the CDP-ethanolamine route leading to phosphatidylethanolamine (PE). Can also catalyze the formation of phosphatidylcholine (PC) from CDP-choline, but does not substantially contribute to PC biosynthesis. Preferentially uses CDP-dimethylethanolamine and CDP-propanolamine as aminoalcohol substrates. Shows highest activity toward di-unsaturated diacylglycerol species as lipid substrates. The CDP-ethanolamine pathway may play a role in maintaining the proper PE species distribution. a 1,2-diacyl-sn-glycerol + CDP-ethanolamine = a 1,2-diacyl-sn-glycero-3-phosphoethanolamine + CMP + H(+) a 1,2-diacyl-sn-glycerol + CDP-choline = a 1,2-diacyl-sn-glycero-3-phosphocholine + CMP + H(+) a 1,2-diacyl-sn-glycerol + CDP-N-methylethanolamine = 1,2-diacyl-sn-glycero-3-phospho-N-methylethanolamine + CMP + H(+) a 1,2-diacyl-sn-glycerol + CDP-N,N-dimethylethanolamine = 1,2-diacyl-sn-glycero-3-phospho-N,N-dimethylethanolamine + CMP + H(+) 1,2-di-(9Z-octadecenoyl)-glycerol + CDP-choline = 1,2-di-(9Z-octadecenoyl)-sn-glycero-3-phosphocholine + CMP + H(+) 1,2-di-(9Z-octadecenoyl)-glycerol + CDP-ethanolamine = 1,2-di-(9Z-octadecenoyl)-sn-glycero-3-phosphoethanolamine + CMP + H(+) Requires a divalent cation activator, and is inhibited by CMP. Activated by phospholipids, especially phosphatidylcholine. Phospholipid metabolism; phosphatidylethanolamine biosynthesis; phosphatidylethanolamine from ethanolamine: step 3/3. Phospholipid metabolism; phosphatidylcholine biosynthesis; phosphatidylcholine from phosphocholine: step 2/2. Repressed by inositol. Repression is dependent on the presence of CPT1. Belongs to the CDP-alcohol phosphatidyltransferase class-I family.