Figure 2. Differential Effect of DNA-PKcs on WRN helicase and exonuclease activities. (A) WRN (3.3 nM, lanes 3-5) and DNA-PKcs (3.3 nM, lane 4; 16.7 nM, lanes 5 and 6) were incubated in standard reaction buffer lacking ATP prior to addition of the D-loop substrate. Reaction products were analyzed by denaturing gel electro-phoresis. Lanes 1 and 7: A DNA ladder marker. (B) WRN (E84A) (3.3 nM, lanes 3-5) was preincubated with either DNA-PKcs (16.7 nM, lane 4) or Ku (3.3 nM, lane 5) in standard reaction buffer prior to addition of the D-loop substrate. Reaction products were analyzed by native gel electrophoresis. Lane 1: heat-denatured D-loop substrate denoted by a filled triangle. Lane 6: A DNA ladder marker.