This enzyme is thought to play an important role in the regulation of methyl group metabolism in the liver and pancreas by regulating the ratio between S-adenosyl-L-methionine and S-adenosyl-L-homocysteine. It is inhibited by 5-methyltetrahydrofolate pentaglutamate [4]. Sarcosine, which has no physiological role, is converted back into glycine by the action of EC 1.5.8.3, sarcosine dehydrogenase.