Figure 3. Complex Structure of E2-25K UBA domain with Ub.

Ribbon representation of the lowest energy complex structure, UBA shown on the left, monoUb shown on the right. Sidechains involved in binding are shown as sticks (UBA: M172, G173, F174, L198 ; Ub: R42, I44, K48, Q49, L71, R72). Surface model of the UBA domain with Ub-binding residues highlighted in black, and surface model of Ub with UBA-binding residues highlighted in black are shown below. Molecules have been rotated outward 90° to expose binding surfaces.