Escherichia coli AlkB is a DNA repair enzyme that represents the founding member of the AlkB family of non-heme iron-dependent dioxygenases. The human genome encodes nine AlkB homologs termed AlkB homolog 1 through 8 (ALKBH1 through 8) plus a ninth member termed fat mass and obesity associated (FTO). Bacterial AlkB as well as human ALKBH2 and ALKBH3 catalyze the direct reversal of DNA methylation damage through a distinct oxidative demethylation reaction. Importantly, ALKBH2 has been shown to play a role in DNA alkylation damage repair in human, mouse and plant cells. Full-length ALKBH2 has a molecular weight of about 30kDa and ALKBH2 variant encoded by an alternatively spliced transcript with a frameshift deletion of the C-terminal dioxygenase domain has a molecular weight of about 25kDa (PMID:22079122).