Figure 1.

(a) Switch from cap-dependent to cap-independent translation. (b) Main features and secondary structure of the picornavirus type II IRES, the HCV IRES, and the dicistrovirus intergenic region (IGR) are represented. The location of domains referred to in the text is indicated. Green stars denote the location of sequences with modified conformational flexibility upon IRES incubation with ribosomal subunits. For type II IRES, the binding site of PTB, PCBP2 and eIF4G are indicated, while for HCV the binding site of eIF3 and the 40S recognition site are depicted.