||p.6 left column paragraph above bottom paragraph:"The error rate in transcription with the wild type trigger loop is on the order of 10^- 6, of which about 10^- 4 may be accounted for by the fidelity of RNA synthesis. The remaining two orders of magnitude are gained by proofreading, in a three-step process. First, the polymerase backtracks to extrude the misincorporated nucleotide. Then, in a reaction assisted by TFIIS, the transcript is cleaved in the active center, releasing a dinucleotide containing the misincorporated residue (Fig. 5). Finally, fresh NTP enters the active center and synthesis resumes, with a chance of only one in 10^4 of repeating the original error." P.6 left column 3rd paragraph:"The trigger loop is a conserved feature of all multisubunit,
DNA-directed RNA polymerases, either observed in structures, such
as that of the T. thermophilus RNAP [ref 71], or indicated by sequence
analysis, as for E. coli and archaeal (M. jannaschii) RNAPs [refs 72,73]."