Simplified diagram of one-carbon metabolism (1-CM) including the methionine cycle, the roles of one-carbon nutrients, and links to lipid metabolism

Simplified diagram of one-carbon metabolism (1-CM) including the methionine cycle, the roles of one-carbon nutrients, and links to lipid metabolism. Methionine (Met) can be synthesized from homocysteine (Hcy) in a reaction catalyzed by betaine-homocysteine methyltransferase (BHMT) using the choline metabolite betaine as the methyl donor. Alternatively, the remethylation of homocysteine to methionine can proceed via the folate and vitamin B-12 dependent methionine synthase (MS) reaction. Choline, betaine, folate, and vitamin B-12 have critical roles in lipid metabolism because they contribute to the production of phosphatidylcholine (PC) via the phosphatidylethanolamine-N-methyltransferase (PEMT) pathway, which is necessary for the formation of very-low-density-lipoproteins (VLDL) and the removal of triglycerides (TGs) from the liver. DMG, dimethylglycine; LDL, low density lipoprotein; MTHFR, 5,10-methylenetetrahydrofolate reductase; PE, phosphatidylethanolamine; SAM, S-adenosylmethionine; SAH, S-adenosylhomocysteine; SHMT, serine hydroxymethyltransferase; THF, tetrahydrofolate.

Publication

Maternal obesity disrupts the methionine cycle in baboon pregnancy. (2015) Peter W Nathanielsz, et al. Physiol Rep. 2015 Nov;3(11):e12564. Figure: F1. All organisms Drosophila melanogaster Homo sapiens

Disease mentions