Figure 1.

Effects of PCNA, RFC, and E. coli SSB on pol δ activity with the poly(dA)⋅oligo(dT) template. Reaction mixtures (30 μl) contained 40 mM Tris⋅HCl (pH 7.8), 7 mM MgCl₂, 2 mM ATP, 0.5 mM DTT, 166 μg/ml BSA, 50 ng poly(dA)₄₀₀₀⋅oligo(dT)_12–18 (20:1), and 33 μM [³H]dTTP (300 cpm/pmol). Where indicated, 0.13 unit of RFC, 50 ng PCNA, 0.3 μg E. coli SSB, and 0.15 unit of pol δ (hydroxylapatite fraction) were added. Reactions were incubated at 37°C for 60 min, and the incorporation of [³H]dTMP into an acid-insoluble form was measured by liquid scintillation counting.