FIGURE 3.

The RQC domain of WRN is necessary for full stimulation of hpol η^1–437 activity. A, hpol η^1–437 (2 nm) DNA synthesis was allowed to proceed for 20 min in the presence of increasing amounts of WRN^{1–1092/E84A} (blue panel) and the products were separated by 16% PAGE, 7 m urea. B, hpol η^1–437 (2 nm) DNA synthesis was allowed to proceed for 20 min in the presence of increasing amounts of WRN^1–949/E84A (magenta panel) and the products were separated by 16% PAGE, 7 m urea. C, full-length product formation shown in panels A and B was quantified. D, DNA synthesis by hpol η^1–437 (2 nm) was monitored over time in the presence of either the HRDC-deletion mutant WRN^{1–1092/E84A} (100 nm) or the RQC-deletion mutant WRN^1–949/E84A (100 nm). The experiments were performed in triplicate and the mean ± S.D. is shown. The single-turnover results for each experiment were fit to a single-exponential equation to yield the following kinetic parameters: WRN^{1–1092/E84A} (■): A = 189 ± 2 nm and k_obs = 1.13 ± 0.05 min⁻¹; WRN^1–949/E84A (▴): A = 192 ± 3 nm and k_obs = 0.38 ± 0.02 min⁻¹. The control experiment with hpol η alone from Fig. 1C was re-plotted for comparison (●).