Betaine Homocysteine Methyltransferase (BHMT)

Betaine-homocysteine methyltransferase (BHMT; EC 2.1.1.5) is a cytosolic enzyme that catalyzes the conversion of betaine and homocysteine to dimethylglycine and methionine, respectively. This reaction is also required for the irreversible oxidation of choline. The sequence of the predicted 406-amino acid human BHMT is 94% identical to that of the porcine protein.Maximal expression was observed when rats consumed diets deficient in methionine yet rich in methyl donors, such as choline, betaine, or sulfonium analogs of betaine.BHMT2 was rapidly degraded when translated in vitro in rabbit reticulocyte lysates. BHMT2 was stabilized by cotransfection of COS-1 cells with BHMT, and after cotransfection, BHMT2 coprecipitated with BHMT.