Methylated-DNA--protein-cysteine methyltransferase (MGMT)

Involved in the cellular defense against the biological effects of O6-methylguanine (O6-MeG) and O4-methylthymine (O4-MeT) in DNA. Repairs the methylated nucleobase in DNA by stoichiometrically transferring the methyl group to a cysteine residue in the enzyme.

This is a suicide reaction: the enzyme is irreversibly inactivated. .