Cryo-EM maps of the degradation intermediates observed from state Deg1 to Deg4. To better illustrate compositional changes between each state, the outline of the RIOK3-40S state is depicted by black dashed lines. Zoomed-in view of the mRNA exit channel in the state Deg1 is shown as an insert at the bottom right. Density maps for the ubiquitin moieties of each state are shown as round inserts at the top right. The 5' (magenta), central (C, orange), 3' major (3'M, cyan), and 3' minor (3'm, green) domains of the 18S rRNA are highlighted. The positions of eS26 and eL41 are indicated. In the RIOK3-40S state, RIOK3's density is shown in dark green.
