Phosphatidylethanolamine N-methyltransferase and regulation of homocysteine.

Homocysteine is a non-protein, sulfur-containing amino acid derived from methionine metabolism and S-adenosylmethionine (SAM)-dependent transmethylation. Elevations in plasma homocysteine have been associated with increased risk of cardiovascular disease, atherosclerosis, birth defects, Alzheimer's disease, and osteoporosis. Of the many known methyltransferases that utilize SAM, phosphatidylethanolamine N-methyltransferase has recently received much attention for its possible role in the regulation of homocysteine.