Fig. 3.

Position of the nascent RNA in the reiterative transcription complex. The overall structure of the RTC is shown with RNAP depicted as a molecular surface model (α, gray; β′, white; σ, orange). RNA, t-DNA, and nt-DNA strands are shown as sphere models and labeled. For clarity, all of the β-subunit except a ribbon model of the lobe domain was removed in A. RNAP motifs discussed in the text are highlighted and labeled. The structure in B is the same as that in A, except that it is rotated clockwise 90°. Bottom shows magnified views of the boxed regions at Top.