FIGURE 2.

Cryo-EM structure of COMPASS bound to the ubiquitinated nucleosome core particle. (A) Cartoon representation of COMPASS cryo-EM structure bound to the ubiquitinated nucleosome in which each subunit is indicated. (B) Zoomed view on the interactions between ubiquitin and the pre-SET domain of SET1. Shown are the polar contacts between RbBP5 WDRP loop and ubiquitin (C) and the cluster of positively charged residues of the SET1 ARM motif interacting with the H2A acidic patch (D) and histone H2B (E). Cartoon representation of RbBP5 N- and C-termini that make contacts with ubiquitin’s hydrophobic patch (depicted as sticks) (F), as well as the contacts made between its β-propeller domain and ubiquitin C-terminal end (G). All figures were prepared using the cryo-EM structure of the COMPASS catalytic module in complex with the ubiquitinated nucleosome (PDB accession number 6UH5).