Catalyzes the methylation of glycine by using S-adenosylmethionine (AdoMet) to form N-methylglycine (sarcosine) with the concomitant production of S-adenosylhomocysteine (AdoHcy). Possible crucial role in the regulation of tissue concentration of AdoMet and of metabolism of methionine.
Abundant in liver.
Defects in GNMT are the cause of glycine N-methyltransferase deficiency (GNMT deficiency) [MIM:606664]; also known as hypermethioninemia. The only clinical abnormalities in patients with this deficiency are mild hepatomegaly and chronic elevation of serum transaminases.
Belongs to the glycine N-methyltransferase family.