Figure 3.

Hydrolysis of mispaired RNA–DNA 3′ ends by RNA pol II with and without TFIIS. The nucleotide sequences of the paired and mispaired dumbbells is given in Fig. 1A and their abbreviated identification is presented on the left. The 5′-labeled dumbbells were incubated with pol II, with and without TFIIS for the indicated times. All cleavage reactions were carried out under identical conditions. The DB2 reaction contained 5% of 40-nt product that could not be removed by two gel electrophoresis purifications. Production of a band corresponding to the 38-nt product demonstrates the presence of the 40-nt product. For quantitation, the radioactivity in each gel band was measured by phosphorimaging (Fuji). The percent of cleavage by pol II in 60 min and pol II with TFIIS in 30 sec and 3 min is presented as a histogram.