Catalyzes both phosphatidylcholine and phosphatidylethanolamine biosynthesis from CDP-choline and CDP-ethanolamine, respectively. Has a higher cholinephosphotransferase activity than ethanolaminephosphotransferase activity. 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(+) Phospholipid metabolism; phosphatidylethanolamine biosynthesis; phosphatidylethanolamine from ethanolamine: step 3/3. Phospholipid metabolism; phosphatidylcholine biosynthesis; phosphatidylcholine from phosphocholine: step 2/2. A number of isoforms are produced. According to EST sequences. Belongs to the CDP-alcohol phosphatidyltransferase class-I family.