RNA extension assays performed on the DNA template in (A). Factors DSIF and NELF were included as indicated. 100 nM of Pol II, 300 nM of DSIF and NELF, and 100 nM of nucleic acids were used. Reactions were quenched at various times after nucleotide addition and were separated on denaturing gels. Positions of the RNA primer, pause site (+2), backtracked site (+3), and full-length product (+7) are indicated. Four reactions, left to right, are shown: Pol II only, Pol II-DSIF, Pol II-NELF, Pol II-DSIF-NELF. Results are representative of three replicates.
