Figure 3.

Model for preinitiation complex (PIC) arrangement at AUG recognition. Three 90° rotated cartoon views of an idealized 48S PIC, modeled on recent structural and functional studies. This model was based on the partial yeast 48S closed complex structure (3JAP) (Llacer et al. 2015) and modified to include findings of others (Luna et al. 2012, 2013; Aylett et al. 2015; des Georges et al. 2015; Simonetti et al. 2016; Obayashi et al. 2017). The entry view (left) shows the eukaryotic initiation factor (eIF)3 yeast-like core subunits, whereas the exit view (right) shows only the mammalian eIF3 octamer complex. eIF2 is shown as semitransparent in the central intersubunit view (middle) to indicate the position of factors otherwise hidden below. For further details of eIF2 interactions, see Figure 4. The position of Rack1 on the ribosome head is shown for orientation purposes only and is not discussed in the text. Factor colors correspond to those used in other figures.