Extended Data Figure 9. Structures of different assembly states of the pre-60S ribosomal particles.

a, Cryo-EM density maps of three premature states (1–3) and the mature state are displayed in transparent surface representation, superimposed with models of the 5S RNA, H38 and associated central-protuberance-binding factors. b, Zoom-in views of the central protuberance regions in a. For clarification, only atomic models are shown. Comparison of these four states indicates that the 5S RNP rotates to a near-mature state (state 2) after Rpf2–Rrs1 leave, and further release of Rsa4 in state 3 results in a ‘mature-like’ conformation for the 5S RNP. H38 from these four states is in a series of continuous changes coupled with the 5S RNP conformational maturation. c, d, Spatial relationship of the 5S RNP, H38, Rsa4 and Cgr1 in state 1 (c) and state 2 (d). Note that repositioning of H38 from state 1 to state 2 is coupled with a dramatic conformational change on the C-terminal end of Cgr1. e–h, Additional assembly factors identified in the density map of state 2. One piece of additional density between H38 and L1 contains a characteristic HEAT repeat, which contacts the L1 stalk in an inward position (e). The atomic model of Sda1 (PDB accession number 5FL8)¹⁴ fits well with the segmented density (f). For clarification, densities immediately above Sda1 are not shown in e and f. A large piece of additional density in the map of state 2, composed of the Rix1 subcomplex and Rea1 (g, h). The density assignment was facilitated by the cryo-EM structure of Rix1–Rea1 particles¹⁴. Superimposition of the atomic model of Rea1 (PDB accession number 5FL8)¹⁴ with the segmented density map of Rea1 (h).