Figure 2.
PAGE (20%, with 7 M urea) of transcription products with four RNA length standards (left, 42, 25, 14, 5 nt). Transcription of “standard template” shows unreacted 32P-GTP (large band at bottom), typical “stutter” bands, full-length transcript (30 nt), and small amounts of very long products (unassigned). Remaining bands are with indicated templates containing from 1 to 3 dPs (Table S1) obtained without rZTP (left cluster) and with rZTP (right cluster). Full-length product is made in the absence of rZTP by misincorporation of a standard nucleotide (presumably rC) opposite dP, with increasing pausing with increasing numbers of template dPs. Pausing disappears when rZTP is added.