Fig. 2.

Dealkylation of O ⁶-methylguanosine and the pseudosubstrate O ⁶-benzylguanine by MGMT. a Following DNA methylation, the methyl group is transferred from O ⁶-methylguanosine to the active centre of MGMT. The same happens if the free base O ⁶-MeG is used as a pseudo-substrate. b In case of O ⁶-BG, the benzyl group is transferred to Cys 145 of MGMT. Alkyl group transfer to MGMT inactivates the protein and subjects it to degradation via ubiquitination