Regulation of phosphatidylcholine biosynthesis by the methylation pathway in rat pituitary gland.

Rat pituitary extracts catalyze methylation of phosphatidylethanolamine to phosphatidylcholine using S-adenosyl-L-methionine as the methyl donor. In vitro incubation of hemipituitaries with 1 mM 2-methylaminoethanol led to a dose dependent decrease in phosphatidylethanolamine methyltransferase activity as well as the incorporation of the radioactivity from [3H-methyl]-L-methionine into phosphatidyl-choline. The inhibitory effect of 2-methylaminoethanol was selective for phospholipids methylation since protein carboxymethyltransferase and catechol-o-methyltransferase activities were not affected.