Figure 3. Helical ubiquitin-binding domain structures.

Ubiquitin molecule (yellow) in ribbon and surface representations is shown with corresponding helical domain (blue) in ribbon representation. Ile⁴⁴, the centre of the hydrophobic recognition patch on the ubiquitin, is shown as green spheres. Ubiquitin molecules are placed in the same orientation as in Figure 1 for comparison. For the UIM, MIU and DUIM structures, both N- and C-termini are marked. Protein data bank identication codes used are as follows: UIM, 1Q0W; MIU, 2FIF; DUIM, 2D3G; Vps9 CUE, 1P3Q; Cue2-CUE, 1OTR; UBA, 1WR1; GAT, 1YD8. Vps9 CUE domain forms a domain-swapped dimer, shown in blue and light blue. The missing part in Vps9 CUE was modelled on the basis of the apo structure.