Figure 4. DNA end binding–defective Ku heterodimers show reduced association with telomeres.

(A) Myc-tagged Yku80 was immunoprecipitated from sheared chromatin prepared from crosslinked cells containing Yku70 or Yku70-R456E. Isolated DNA was analyzed by dot-blot with a radiolabeled telomere specific probe or TyB probe for nonspecific association. The mean percentage of telomeric DNA immunoprecipitated in five trials is shown +/- one SD. (B) Western blot showing equivalent Yku80_myc18 immunoprecipitation efficiency in the YKU70 and yku70-R456E samples. α-PGK serves as a control for protein levels in input WCEs prior to immunoprecipitation.