This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
|Superclasses:||Biosynthesis → Fatty Acid and Lipid Biosynthesis → Phospholipid Biosynthesis → Phosphatidylcholine Biosynthesis|
Expected Taxonomic Range: Viridiplantae
Phosphatidylcholine is one of the major constituents of membrane phospholipids (see superpathway of phospholipid biosynthesis II (plants)). The phosphatidylcholine biosynthetic pathways vary among different organisms.
There are at least four alternative routes have been reported in plants. Two additional routes were reported in animals [Schneider79] and bacteria [Sohlenkamp00] (see pathways phosphatidylcholine biosynthesis V and phosphatidylcholine biosynthesis VI).
1) The Kennedy pathway ( phosphatidylcholine biosynthesis I) depends on choline kinase and on the availability of choline.
2) The second pathway ( phosphatidylcholine biosynthesis II) depends on three consecutive N-methylation steps that are carried out on phospho-bases, phosphoethanolamine, phospho-N-methylethanolamine, and phospho-N-dimethylethanolamine.
3) The third pathway (depicted here) depends on an initial N-methylation with phospho-base phosphoethanolamine, and followed by two downstream N-methylations on phosphatidyl-bases, phosphatidyl-N-methylethanolamine and phosphatidyl-N-dimethylethanolamine. In plants, phosphatidyl-N-methylethanolamine is believed to be derived from CDP-methylethanolamine, whereas in animals, it is a direct methylation product from phosphatidylethanolamine [Schneider79].
4) The fourth pathway ( phosphatidylcholine biosynthesis IV) depends on two N-methylations with phospho-base phosphoethanolamine and phospho-N-methylethanolamine, followed by a downstream N-methylation on phosphatidyl-base phosphatidyl-N-dimethylethanolamine.
Radio tracer experiments with crude cell extracts suggested such a pathway in soybean and carrot [Datko88a].
Variants: phosphatidylcholine biosynthesis I, phosphatidylcholine biosynthesis II, phosphatidylcholine biosynthesis IV, phosphatidylcholine biosynthesis V, phosphatidylcholine biosynthesis VI, phosphatidylcholine biosynthesis VII, phospholipid remodeling (phosphatidylcholine, yeast)
Schneider79: Schneider WJ, Vance DE (1979). "Conversion of phosphatidylethanolamine to phosphatidylcholine in rat liver. Partial purification and characterization of the enzymatic activities." J Biol Chem 254(10);3886-91. PMID: 438165
Sohlenkamp00: Sohlenkamp C, de Rudder KE, Rohrs V, Lopez-Lara IM, Geiger O (2000). "Cloning and characterization of the gene for phosphatidylcholine synthase." J Biol Chem 275(25);18919-25. PMID: 10858449
Bolognese00: Bolognese CP, McGraw P (2000). "The isolation and characterization in yeast of a gene for Arabidopsis S-adenosylmethionine:phospho-ethanolamine N-methyltransferase." Plant Physiol 124(4);1800-13. PMID: 11115895
Boumann04: Boumann HA, Chin PT, Heck AJ, De Kruijff B, De Kroon AI (2004). "The yeast phospholipid N-methyltransferases catalyzing the synthesis of phosphatidylcholine preferentially convert di-C16:1 substrates both in vivo and in vitro." J Biol Chem 279(39);40314-9. PMID: 15258140
Cui93: Cui Z, Vance JE, Chen MH, Voelker DR, Vance DE (1993). "Cloning and expression of a novel phosphatidylethanolamine N-methyltransferase. A specific biochemical and cytological marker for a unique membrane fraction in rat liver." J Biol Chem 268(22);16655-63. PMID: 8344945
Gaynor90: Gaynor PM, Carman GM (1990). "Phosphatidylethanolamine methyltransferase and phospholipid methyltransferase activities from Saccharomyces cerevisiae. Enzymological and kinetic properties." Biochim Biophys Acta 1045(2);156-63. PMID: 2198947
Hacker08: Hacker S, Sohlenkamp C, Aktas M, Geiger O, Narberhaus F (2008). "Multiple phospholipid N-methyltransferases with distinct substrate specificities are encoded in Bradyrhizobium japonicum." J Bacteriol 190(2);571-80. PMID: 17993534
Kodaki87: Kodaki T, Yamashita S (1987). "Yeast phosphatidylethanolamine methylation pathway. Cloning and characterization of two distinct methyltransferase genes." J Biol Chem 262(32);15428-35. PMID: 2445736
Kodaki89: Kodaki T, Yamashita S (1989). "Characterization of the methyltransferases in the yeast phosphatidylethanolamine methylation pathway by selective gene disruption." Eur J Biochem 185(2);243-51. PMID: 2684666
McGraw89: McGraw P, Henry SA (1989). "Mutations in the Saccharomyces cerevisiae opi3 gene: effects on phospholipid methylation, growth and cross-pathway regulation of inositol synthesis." Genetics 122(2);317-30. PMID: 2670666
Nuccio00: Nuccio ML, Ziemak MJ, Henry SA, Weretilnyk EA, Hanson AD (2000). "cDNA cloning of phosphoethanolamine N-methyltransferase from spinach by complementation in Schizosaccharomyces pombe and characterization of the recombinant enzyme." J Biol Chem 275(19);14095-101. PMID: 10799484
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