FIGURE 4.

SO increases nucleotide misinsertion and misextension by Pol η. Pol η (0.6 nm) was incubated with DNA P/T1 (10 nm) in the presence of single dNTPs (either correct (dCTP) or incorrect (dATP, dGTP, dTTP) (A)) or three of four dNTPs (B), each at 100 μm concentrations. Extension reactions were carried out at 37 °C for 10 min in the absence (−) or presence (+) of 8 μm sphingosine. Note the strong pause sites at or immediately preceding the missing dNTP. S, substrate (−) enzyme; N, control with all four dNTPs. The sequence of the DNA template is shown on the left.