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. 2010 Nov 26;30(1):115–129. doi: 10.1038/emboj.2010.302

Figure 7.

Figure 7

Models for stem bypass by the scanning 43S complex. (A) Canonical 48S complex formation involving unwinding of a stem. (B, C) Models for 48S complex formation on AUG triplets (B) upstream and (C) downstream of stable stems without stem unwinding. (C) The bypass mechanism should be the same as in (B), except that the stem also moves past the Entry channel and the A and P sites. Stems (either intact or unwound) are shown in red. The positions of the ribosomal A, P and E sites and the 3′/5′ polarity of mRNA are shown in the left panel. The direction of mRNA movement with respect to the 40S subunit is indicated with arrows. The start codon is shown as ‘AUG'. Suppression of stem bypass by DHX29 and of formation of aberrant 48S complexes with an intact stem near the Exit channel by eIF1 are indicated by ‘⊣' in panel (C).