Fig. 7. Translesion synthesis by in vitro synthesized wild-type and S62G hPolη proteins on an unmodified template and templates containing site-specific lesions. Bypass of five lesions in the same DNA sequence context was compared in primer extension assays. The template contained either no lesion, 8-oxo-G, O⁴-MeT, O⁶-MeG, an abasic site or ethenoA. The position of the lesion (∗) was three nucleotides downstream of the 3′ primer terminus (arrow). The assays, containing 2 µl of a 1:20 dilution of in vitro synthesized wild-type or mutant hPolη, were terminated at different times, as indicated, by addition of formamide. The elongated products observed at time 0 probably reflect limited incorporation at 4°C.