Phosphatidylethanolamine N-methyltransferase

Figure 1. Pathways for the synthesis of phosphatidylcholine, phosphatidylethanolamine and sphingomyelin. Abbreviations CK, choline kinase CPT, cholinephosphotransferase CT, CTP phosphooholine cytidylyltransferase DAG, diacylglycerol PC, phosphatidylcholine PE, phosphatidylethanolamine PEMT, phosphatidylethanolamine-N-methyltransferase SM, sphingomyelin SMase, sphingomyelinase SMsyn, sphingomyelin synthase.

Houweling, M., Cui, Z., and Vance, D.E., 1995, Expression of phosphatidylethanolamine N-methyltransferase-2 cannot compensate for an impaired CDP-choUne pathway in mutant Chinese hamster ovary cells. J. Biol. Chem. 270 16277-16282 Ishidate, K.. 1997, Chohne/ethanolamine kinase from mammalian tissues. Biochim. Biophys. Acta 1348 70-78... 

Uckun, P.M., Schieven, G.L., Tuel-Ahlgren, L.M., Etihirdik, L, Myers, D.E., Ledhetter, J.A., and Song, C.W., 1993, Tyrosine phosphorylation is a mandatory proximal step in radiation induced activation of the protein kinase C signaling pathway in human B-lymphocyte precursors. Proc. Natl. Acad Sci. U.S.A. 90 252-256 Vance, D.E., Walkey, C.J., and Cui Z, 1997, Phosphatidylethanolamine N-methyltransferase from tiver. Biochim. Biophys. Acta 1318 142-150... 

PHOSPHATIDYLINOSITOL SYNTHASE Phosphatidyl-N-methylethanolamine, PHOSPHATIDYLETHANOLAMINE N-METHYLTRANSFERASE PHOSPHATIDYL-N-METHYLETHANOL-AMINE N-METHYLTRANSFERASE... 

The major (salvage) pathways for the formation of phosphatidylcholine and ethanolamine are illustrated in Figure 19.16. Free (dietary) choline and etha-nolamine are converted to their CDP derivatives, which then react with diacyl-glycerol to form phosphatidylcholine and ethanolamine. In the lungs, another pathway forms dipalmitoyl phosphatidylcholine, a powerful surfactant. Phos-phatidylethanolamine may be methylated by S-adenosylmethionine (SAM see Chapter 20) to yield phosphatidylcholine. The reaction is catalyzed by two enzymes the first methyl group is transferred via phosphatidylethanolamine N-methyltransferase I. The other two methyl groups are transferred by phosphatidylethanolamine N-methyltransferase II. Some authorities believe that the two enzymes are identical. It has also been proposed that methylation of phospha-... 

Phosphatidylcholine can also be synthesized by the methylation pathway that converts phosphatidylethanolamine to phosphatidylcholine, principally in the liver. The methyl donor is S-adenosylmethionine (Chapter 17). Phosphatidylethanolamine-N-methyltransferase transfers three methyl groups in sequence to produce phosphatidylcholine. The fatty acid components of phosphatidylcholine can then be altered by deacylation-reacylation reactions. 

Vance, D.E., Li, Z. and Jacobs, R.L. (2007) Hepatic phosphatidylethanolamine N-methyltransferase, unexpected roles in animal biochemistry and physiology. J. Biol. Chem. 282, 33237-33241. 

Kanchanarach W, Theeragool G, Inoue T, Yaknshi T, Adachi O, Matsushita K (2010) Acetic acid fermentation of Acetobacter pasteurianus relationship between acetic acid resistance and pellicle polysaccharide formation. Biosci Biotechnol Biochem 74(8) 1591-1597 Kaneshiro T, Law JH (1964) Phosphatidylcholine synthesis in Agrobacterium tumefaciens. I. Purification and properties of a phosphatidylethanolamine N-methyltransferase. J Biol Chem 239 1705-1713... 

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