Figure 3.

Effects of hMRE11-knockdown on DNA mismatch repair (MMR). A 50 μg portion of nuclear extracts derived from parental HeLa (H) and HeLa 14 (Hⁱ) cells and 17.6 μg of a partially purified hMRE11-enriched HeLa nuclear fraction SS1 were used to perform MMR reactions with 5′ G-T and 3′ G-T mismatch substrates. Repaired products were distinguished from substrates by restriction digestion, and repair efficiency was scored by dividing repaired products with the total substrate DNA. (A) MMR reactions were performed as indicated. The hMRE11-enriched SS1 fraction is defective for both 3′ and 5′ repairs. (B) Average repair efficiencies and standard deviations (error bars) were determined from three independent data points. ^*P=0.003, ^**P=0.007, t-test.