ALKBH4 (alkB, alkylation repair homolog 4), also known as ABH4, is a 302 amino acid protein belonging to the alkB family. ALKBH4 is one of many homologs of the Escherichia coli protein AlkB. AlkB functions to protect DNA and RNA against damage from environmental methylating compounds by directly reversing 1-methyladenine (1-meA) and 3-methylcytosine (3-meC) cytotoxic alkylation lesions in DNA and RNA. The enzyme acts by oxidative demethylation, utilizing ferrous iron and alpha-ketoglutarate as cofactors, 2-oxoglutarate as a co-substrate and molecular oxygen as the oxidizing agent. ALKBH4 exists as two alternatively spliced isoforms and is encoded by a gene located on human chromosome 7, which houses over 1,000 genes and comprises nearly 5% of the human genome.
