Figure 6.

Binding of Pol δ^DV to PCNA relieves all inhibitory effects on strand displacement and masks the activity of the secondary site on the polymerase. (a) PCNA was loaded on DNA substrates containing streptavidin bumpers using RFC and ATP. The reactions were started by adding Pol δ^DV with dNTP. For these experiments T₇ gap substrates with the indicated length of a 5′-flap were used. (b) After loading of PCNA onto a T₇ gap substrate that does not contain a 5′-flap, the reactions where started either by addition of a solution of Pol δ^DV and dNTP with or without a 10-fold excess of dT₂₅ or by first adding Pol δ^DV for 1 min followed by the addition of dNTP with or without a 10-fold excess of dT₂₅.