 Abasic sites can react with amine groups on proteins to form DNA-protein crosslinks or with exocyclic amines of other nucleobases to form interstrand crosslinks.To prevent interstrand or DNA-protein crosslinks, enzymes from the BER pathway tightly bind the abasic site and sequester it from nearby reactive groups, as demonstrated in human alkyladenine DNA glycosylase (AAG) and "E. coli" 3-methyladenine DNA glycosylase II (AlkA).