FIGURE 6.
DNA end breathing provides a substrate for Artemis 5′ exonuclease activity. Shown is the time course of Artemis activity on blunt-ended and fixed 2-nt Y-structure DNA. 20 nm 5′ 32P-radiolabeled, 34-bp biotinylated-dsDNA (B) was incubated with 50 nm Artemis and 0.1 μm streptavidin (SA) for 0, 15, 30, and 60 min at 37 °C. The samples were resolved on a 12% denaturing PAGE. Substrates were blunt-ended dA (*HC79/82, lanes 1–4), dA Y-structure (*HC98/76, lanes 5–8), blunt-ended dG (*HC80/83, lanes 9–12), and dG Y-structure (*HC99/84, lanes 13–16). Asterisk, [32P]-phosphate. The quantified 5′ resection percentage is noted at the bottom of the gel. This is a representative gel of at least two identical experiments.