Figure 6. Reconstitution assay using purified BER proteins.
(A) Wild-type (WT) and variant APE1 proteins were incubated with UDG and POLβ with 32P-labeled 34U DNA substrate (1 pmol), and the reactions were resolved on a urea-polyacrylamide denaturing sequencing gel. The non-incised substrate (S), AP site incision product (P1), and gap-filling extension product (P2) were visualized and quantified using standard phosphorimaging analysis. NE = no enzyme. (B) Relative AP site cleavage efficiency. Shown are the averages and standard deviations of 4 independent reactions. (C) Relative gap-filling activity. Shown are the average and standard deviation of 4 independent assays.