Kinetic analysis of single nucleotide incorporation by Pol η. Steady state reactions to measure kinetic constants were carried out as described under “Experimental Procedures.” A representative gel (A) and the corresponding Michealis-Menten graphs (B) show the incorporation of the correct nucleotide, dCTP (concentrations ranging from 0.5–10 μm) by Pol η as a function of the indicated concentrations of SO. 9, 6, and 4.5 fmol of Pol η were used in reactions with 0, 2, and 4/8 μm SO, respectively.