CTP:phosphocholine cytidyltransferase

Yao, Z., JamU, H., and Vance, D. E. (1990). Choline deficiency causes translocation of CTP phosphocholine cytidyltransferase from cytosol to endoplasmic reticulum in rat liver. /. Biol. Chem. 265,4326-4331. 

Arnold RS, Cornell RB. Lipid regulation of CTP phosphocholine cytidyltransferase electrostatic, hydro-phobic and synergistic interactions of anionic phospholipids and diacylglycerol. Biochemistry 1996 35 9917-9924. 

The major pathway of phosphatidylcholine (lecithin) synthesis is via preformed choline (Fig. 15.5). Phosphotidylethanolamine can be converted to phosphatidylcholine in a minor pathway by the addition of 3CH3 groups (from methionine). Thus, phosphatidylcholine can be synthesized de novo if choline is not available and there is a source of "CH3" groups. In a major pathway, phosphatidylcholine can also be synthesized more directly starting with choline. Choline can be phosphorylated with ATP to form phosphocholine. Phosphocholine can react, via phosphocholine cytidyltransferase, in the presence of CTP, to form CDP choline + pyrophosphate, which is pulled in the forward direction by hydrolysis of the pyrophosphate. The CDP choline then can react with diacylglycerol to form phosphatidylcholine and CMP. This reaction is catalyzed by the enzyme phosphocholinetransferase. The major role of phospholipids in cell membranes is discussed in Chapter 4. 

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