Cul3SPOP (a) Schematic representation of the assembly of the Cul3-SPOP E3 ligase: ubiquitin (Ub) in purple, E2 ligase (E2) in dark blue, Ring Box Protein 1 (Rbx1) in yellow, Cullin-3 (Cul3) in magenta, substrate protein (S) in grey, and adaptor protein SPOP shown as the three domains: MATH in light blue, BTB in green, and BACK in orange. Protein assembly I is the PyMOL cartoon representation of the three domains that make up SPOP as found in PDB code 3HDI. Protein assembly II is the 3D representation of the fragment of Cul3 bound to the BTB domain as found in PDB code 4EOZ. (b) 3D representation of the dimerization of SPOP as found in PDB code 3HDI.