title: Synthesis of lecithin (phosphatidylcholine) from phosphatidylethanolamine in bovine brain.
abstract: Choline molecules are needed for the synthesis of acetylcholine and phospholipids in the mammalian brain. An enzymatic activity capable of forming lecithin (phosphatidylcholine) from the step-by-step methylation of phosphatidylethanolamine is identified in the bovine brain. This enzyme(s), phosphatidylethanolamine-N-methyltransferase (EC 2.1.1.17), is localized in the synaptosomal fraction of bovine caudate nucleus, uses S-adenosylmethionine as the methyl donor (apparent Km = 20 micrometers), and has a Vmax of 50--60 pmol/mg protein X h (i.e. about 1% of that found in rat liver). The brain may be able to meet some of its choline requirements by de novo synthesis.
mesh_terms: D000818:Animals; D002417:Cattle; D002421:Caudate Nucleus / Q000201:enzymology*; D007700:Kinetics; D008745:Methylation; D008780:Methyltransferases / Q000378:metabolism; D010713:Phosphatidylcholines / Q000096:biosynthesis*; D050918:Phosphatidylethanolamine N-Methyltransferase; D010714:Phosphatidylethanolamines / Q000378:metabolism*; D013574:Synaptosomes / Q000201:enzymology
chemical_list: D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D008780:Methyltransferases; C494489:PEMT protein, human; D050918:Phosphatidylethanolamine N-Methyltransferase