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. 1997 Sep 16;94(19):10110–10115. doi: 10.1073/pnas.94.19.10110

Figure 3.

Figure 3

Progression in RNA folding as revealed by the decreasing accessibility of the maturation start to ribosomes. Full-length transcripts result from primer extension on 30S-free RNA. Toeprint refers to primer extension stopped by the presence of a 30S initiation complex on the maturation start. Parallel sequence lanes, not present in this audioradiogram, show the reverse transcription to stop at position +16 relative to the first G of the start codon (6). (Left) MS2 RNA covering nucleotides 1–222. (Right) The same MS2 RNA, but the arms of the cloverleaf are replaced by a 5 nt loop (as shown in Fig. 1D). In the absence of tRNAfMet, the 30S subunit is displaced by reverse transcriptase. Full length in ΔSA 1–222 is 72 nt shorter than in MS2 RNA 1–222. When MS2 RNA 1–222 was renatured by slowly cooling from 70°C to 37°C, the toeprint intensity was the same as measured here after 20 min of renaturation.