Figure 5.

Arrest can be induced on templates which otherwise fail to support arrest by disrupting the formation of upstream secondary structure. Templates were transcribed and size markers were generated (from the NA2 template) as described in Materials and Methods. Sequences from transcription start through the 50 bp of inserted sequence are listed in the lower part of the figure for each template. The sequence of the TH2ACdis oligo is shown above the region of the TH1AC and TH2AC sequences to which it anneals. This oligo was added at the indicated concentrations in lanes 4–7 and 14–17. Asterisks mark the bases that have been changed between the TH1AC/TH2AC and TH18/TH14 initially transcribed sequences. Large dots above the sequences indicate the positions where arrest occurred.