Involvement of CDP-choline in phospholipid metabolism of brain tissue in vitro.

The ability of phosphorylcholine and CDP-choline to act as lipid precursors was tested in chick brain microsomes (plus supernatant). CDP-choline was, in every case, a much better precursor of choline glycerophospholipids than phosphorylcholine. The cytidylyltransferase reaction which forms CDP-choline appears, therefore, as the limiting step of the metabolic pathway which introduces phosphorylcholine into lipids. This reaction can be stimulated by the addition of phospholipids to the incubation mixture. Choline lysoglycerophospholipids are the most active in this connection.