“…A central assembly factor already present on the earliest pre-60S particles is Erb1, for which a large number of biochemical, structural, and genetic data have been obtained in previous studies ( Konikkat et al., 2017 , Miles et al., 2005 , Thoms et al., 2016 , Wegrecki et al., 2015 ). It is composed of an N-terminal region containing the nuclear localization signal, a long N-terminal stretch, and a C-terminal β-propeller domain ( Konikkat et al., 2017 , Pestov et al., 2001 , Thoms et al., 2016 , Wegrecki et al., 2015 ). Whereas part of its N terminus is already visible in states A–C, most of Erb1 (amino acids 125 to 807 of 807) can only be seen in the states D and E particles ( Figure 3 A).…”