Figure 3. Structural basis for NEDD8 E1 ufd’s binding to varying E2 sequences.

A, Overall structure of NE1^ufd-UBE2F^core (left) compared to NE1^ufd-UBE2M^core (Huang et al., 2005) (right). NE1^ufd is red, UBE2F^core grey, UBE2M^core cyan, and E2 catalytic cysteines orange spheres. B, UBE2F^core and UBE2M^core structural superposition. C, Close-ups of NE1^ufd-UBE2F^core (left) and NE1^ufd-UBE2M^core (right) interfaces. Oxygens are red, nitrogens blue, ionic interactions dashed. E2 residues are labeled in blue, and NE1^ufd’s in black. X – Leu394SeMet. D, Structural superposition of the NE1^ufd portions of NE1^ufd-UBE2F^core and NE1^ufd-UBE2M^core.