Homocysteine S-methyltransferase (HMT)

Homocysteine S-methyltransferase enzymes catalyze the remethylation of homocysteine to methionine, a critical reaction in methionine and one-carbon metabolism[2][1][4]. Key forms include Betaine-homocysteine S-methyltransferase (BHMT), which uses betaine as a methyl donor primarily in the liver and kidney, and Methionine synthase (MTR), which uses methylcobalamin and 5-methyltetrahydrofolate as substrates and is present throughout various tissues[1][4][2]. These enzymes regulate homocysteine concentrations, and disruptions in their activities can lead to hyperhomocysteinemia, a recognized risk factor for cardiovascular disease, neural tube defects, and certain neuropsychiatric disorders[4]. BHMT and MTR have roles in metabolite repair and S-adenosylmethionine metabolism as well[2]. The broader term "homocysteine methyltransferase" encompasses more than one specific protein and should be mapped to the most relevant, well-characterized enzyme for structured data applications.

Other names

Betaine-homocysteine S-methyltransferaseMethionine synthaseHomocysteine methyltransferaseHomocysteine S-methyltransferaseBHMTMTR

Catalysis of methyl group transfer to homocysteine to form methionine (using methyl donors such as S-adenosylmethionine, S-methylmethionine, or betaine); Regulation of homocysteine and methionine metabolic cycles