Fig. 9.

The flap loop does not contribute to DSIF/NELF-mediated inhibition of transcript elongation. (A) Sequence of the nucleic acid scaffold used to reconstitute ECs. The positions of the halted A24 EC and the runoff transcript (RO) are indicated. (B) (Left) A24 ECs made with wild-type or ΔFL ettRNAPII were elongated in the absence or presence of DSIF/NELF (D/N) and in the presence of all 4 NTPs (10 μM each). Aliquots were removed at predetermined time intervals, and RNA was separated on a 15% denaturing polyacrylamide gel. (Center) Densitometric plot of the distribution of RNA species in the lanes representing the 15-s time point in the absence (solid lines) or presence (dashed lines) of DSIF/NELF. (Right) Bar graph showing the fractions of the 24-mer and runoff RNAs for WT or ΔFL ettRNAPII in the absence (solid bars) or presence (shaded bars) of DSIF/NELF.