FIG. 6.
Effect of pcna-79 and pcna-90 on the 3′→5′ exonuclease activity of Apn2. Apn2 (2 nM) was assayed on a 27- and 75-nt primer-template partial duplex DNA (20 nM), wherein the 5′ 32P-labeled primer was recessed on both ends, for 10 min at 30°C. Reactions were carried out at a 150 mM NaCl concentration and in the presence of RFC (5 nM) and RPA (50 nM) plus wild-type PCNA (lane 2), pcna-79 (lane 3), or pcna-90 (lane 4) (50 nM each), as indicated. No PCNA was added in lane 1. The percentage of primer hydrolyzed by Apn2 was quantitated by a phosphorimager.