DNA-3-methyladenine glycosylase also known as 3-alkyladenine DNA glycosylase (AAG) or N-methylpurine DNA glycosylase (MPG) is an enzyme that in humans is encoded by the MPG gene. Alkyladenine DNA glycosylase is a specific type of DNA glycosylase. This subfamily of monofunctional glycosylases is involved in the recognition of a variety of base lesions, including alkylated and deaminated purines, and initiating their repair via the base excision repair pathway. To date, the human AAG (hAAG) is the only glycosylase identified that excises alkylation-damaged purine bases in human cells.