Figure 9.

Physical and genetic interactions provide clues about the location of the B-factors in pre-ribosomes. (A) Predicted locations of B-factors in assembling 60S subunits. Binding sites of proteins were predicted using a combination of genetic and physical interactions and then superimposed on a schematic of the 60S subunit viewed form the intersubunit side. Grey circles indicate assembly factors and ribosomal proteins that were used as landmarks to help position the B-factors. Genetic interactions listed in Supplementary Table S3 are indicated. PCA, protein complementation assay; H.C. sup, high-copy suppressor; Sup, extragenic suppressor; sl⁻, synthetic lethal. (B) r-proteins such as L4, L15 and L18 are shown in the crystal structure of the 60S subunit as viewed from the crown view of the intersubunit face rotated right 90°. Domains I and III of 25S rRNA are indicated in red and blue, respectively. The Nop7 binding site determined by Granneman et al. (56) is shown in cyan. Pymol images of the ribosome structure were generated using PDB files 3U5H and 3U5I.