This gene belongs to the methyltransferase superfamily and is located in the pseudoautosomal region (PAR) of the X and Y chromosomes. The encoded enzyme catalyzes the final reaction in the synthesis of melatonin and is abundant in the pineal gland. Two amino acid substitutions (R78G and R242C) are p
resent in the encoded protein derived from the reference strain, C57BL/6J, and this protein shows low enzyme activity relative to the protein derived from other strains. [provided by RefSeq, May 2015]