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. 2018 Aug 8;46(18):9816–9828. doi: 10.1093/nar/gky723

Figure 4.

Figure 4.

Inhibition of pol η holoenzyme by p15 (A) Time course of the reaction of pol η in the presence of PCNA/p15 at equimolar concentrations (Lanes 2 and 3), in the presence of PCNA (Lanes 4 and 5), or with pol η alone (lanes 6 and 7) on a cisPt(GG) template (10 nM), with all four dNTPs at the indicated concentration. (B) Time course of the reaction of pol η on the template without the lesion (10 nM), in the presence of PCNA/p15 at equimolar concentrations (lanes 2–5), in the presence of PCNA (lanes 6–9), or pol η alone (lanes 10–13), with all four dNTPs at the indicated concentration. (C) Reaction of pol η replicating the undamaged template in the presence of PCNA and in the absence or presence of p1541–72 peptide or full length p15. Reactants at the indicated concentrations were incubated at 37°C for 30 s and the reaction was stopped by addition of standard denaturing gel loading buffer. In all these experiments, PCNA was not ubiquitylated. These experiments show that p15 downregulates the activity of pol η–PCNA holoenzyme in bypassing a cisplatin lesion as well as in replicating a normal DNA substrate.