Arsenic, 3-Oxidation State Methyltransferase (AS3MT)

AS3MT catalyzes the transfer of a methyl group from S-adenosyl-L-methionine (AdoMet) to trivalent arsenical and may play a role in arsenic metabolism . AS3MT encodes a 375-amino acid protein with 76% amino acid identity to rat As3mt.

The deduced 369-amino acid rat protein has a calculated molecular mass of about 41 kD and contains 2 methyltransferase motifs. RT-PCR analysis of adult rat tissues detected expression in heart, adrenal, urinary bladder, brain, kidney, lung, and liver. Human AS3MT was expressed in a hepatoma cell line but not in an immortalized human urothelial cell line. Recombinant rat As3mt catalyzed the transfer of methyl groups from AdoMet to trivalent arsenicals, resulting in methylated and dimethylated arsenicals.