FIGURE 4.

aRPA does not confer structure-specific endonuclease activity to XPF-ERCC1. A, schematic of XPF junction cutting assay. A 3′-labeled (circle) 70-mer DNA containing a central 20-nt unpaired region was incubated in reactions containing RPA or aRPA and XPF-ERCC1. Junction cutting activity by the XPF endonuclease was detected by electrophoresis of substrate on a denaturing polyacrylamide gel. B, sample incision assay containing XPF-ERCC1 (7.5 ng) and increasing amounts of either RPA or aRPA (0, 5, 10, 20, and 40 ng). C, quantification of data from panel B.