O6-alkylguanine DNA adduct

O6-alkylguanine DNA adducts are DNA lesions formed when an alkyl group is covalently attached to the oxygen atom at the sixth position of the guanine base in DNA. These adducts are generated by exposure to alkylating agents, including certain environmental toxins, chemotherapy drugs (notably nitrosoureas, procarbazine, dacarbazine), and some industrial chemicals. O6-alkylguanine, particularly O6-methylguanine, is highly mutagenic and carcinogenic because it mispairs with thymine during DNA replication, leading to transition mutations[2][4][5]. In cells, the DNA repair protein O6-alkylguanine-DNA alkyltransferase (AGT; also called MGMT) can reverse this lesion in a single step by transferring the alkyl group to its active site cysteine, but this capacity is limited and overwhelmed with high levels of damage[4][5][6]. The DNA adduct itself is not a druggable target or conventional biomolecule, but its presence in DNA is highly biologically significant for mutagenesis, cancer risk, and resistance to chemotherapy. Measurement of O6-methylguanine in tissues or blood is used as a biomarker for exposure to methylating carcinogens and for monitoring the activity of alkylating chemotherapy[2][5]. Note: O6-alkylguanine DNA adducts are not proteins, receptors, or enzymes—they are molecular lesions created by the action of exogenous chemicals or drugs. The therapeutic molecular target associated with their repair is O6-alkylguanine-DNA alkyltransferase (AGT / MGMT)[4][5]. If you require structured data for a repair enzyme, refer to *O6-alkylguanine-DNA alkyltransferase* rather than the adduct. Is_incorrect is TRUE because "O6-alkylguanine DNA adduct" is not a molecular target in the conventional sense but a type of DNA damage/lesion[2][5].

Other names

O6-alkylguanine lesionO6-methylguanine DNA adductO6-alkylG DNA adduct

not applicable (adducts are not molecular targets, but products of chemical or drug interactions)