Figure 2. Comparison of AP endonuclease and NIR activities of WT and mutant APE1 proteins.

[³²P]-labeled THF•T and αdA•T were incubated with WT or varying amounts of mutant APE1 proteins under BER and NIR conditions, and products of the reaction were analyzed using denaturing PAGE. (A) WT and K98A/R185A double APE1 mutant. (B) WT and D308A APE1 mutant. 30mer (31mer in panel B) and 10mer (pX-20mer in panel B) indicate a substrate and cleavage product, respectively. The asterisk denotes the position of a radiolabel. For details, see Methods .