Figure 1.

Models of different forms of cap-dependent translation and for comparison, two models of cap-independent translation. Not all factors are shown for clarity and positioning of factors in the complexes is approximate. The m⁷G cap is depicted as a grey ring system on the 5ʹ end of the RNAs. Circularization of RNAs is traditionally considered to be accomplished via the 3ʹ poly(A) tail, but this is controversial (see text). For panels G & H, there are multiple forms of IRES (G) and CITE (H) translation, only one modality of each is shown here. In panel G, RBP (RNA binding protein) represents a multitude of factors that can be co-opted for translation.