FIG. 5.
The Ku80 carboxy terminus stimulates Artemis-mediated DNA end processing. (A) In vitro hairpin processing assay. In the left panel, a hairpin opening requires the presence of both Artemis and Ku70/80. In the right panel, the hairpin opening activity is significantly reduced when Ku70/Ku80-598 is used instead of Ku70/Ku80-WT. Equal amounts of Ku70/Ku80-598 and Ku70/Ku80-WT were used. (B) Titration of Ku70/Ku80-WT in the hairpin opening assay. Even when Ku70/Ku80-WT is used at a 10-fold-lower concentration than Ku70/Ku80-598, the hairpin opening is still markedly more prevalent in the Ku70/Ku80-WT reaction. From left to right, the Ku70/Ku80-WT concentrations were 10, 5, 2.5, and 1 ng/μl, while Ku70/Ku80-598 was present at 10 ng/μl.