Anti-MGMT antibodies are used in the immunodetection of the protein O-6-methylguanine-DNA methyltransferase. In humans, the canonical protein has a reported length of 207 amino acid residues and a mass of 21.6 kDa. Its subcellular localization is in the nucleus. It is notably widely expressed in many tissue types. A member of the MGMT protein family, MGMT is reported to be involved in cellular defense against the biological effects of O6-methylguanine (O6-MeG) and O4-methylthymine (O4-MeT) in DNA. Synonyms for this target antigen include 6-O-methylguanine-DNA methyltransferase, O-6-methylguanine-DNA-alkyltransferase, methylguanine-DNA methyltransferase, and methylated-DNA--protein-cysteine methyltransferase. MGMT gene orthologs have been reported in the mouse, rat, bovine, frog, zebrafish, chimpanzee and chicken species.