Monomeric RING E3 ligases. (a) CHFR E3 ligase. I is the schematic representation of the assembly of the CHFR E3 ligase: ubiquitin (Ub) in purple, E2 ligase (E2) in dark blue, Ring domain (RING) in yellow, substrate recognition domain FHA (FHA) in light blue, substrate protein in grey, and the cysteine rich domain (CRD) in orange. Protein assembly II is the 3D representation of the monomeric and dimeric conformations of FHA as found in PDB code 1LGQ. Protein assembly III is the 3D representation of the CRD domain as found in PDB code 2XP0. (b) PIRH2 E3 ligase. I is the Schematic representation of the assembly of the PIRH2 E3 ligase: ubiquitin (Ub) in purple, E2 ligase (E2) in dark blue, Ring domain (RING) in yellow, the N-terminal domain (NTD) in turquoise, the C-termina domain (CTD) in light blue, and the substrate protein in grey. Protein assembly II is the 3D representation of the NTD as found in PDB code 2K2C. Protein assembly III is the 3D representation of the RING domain as found in PDB code 2JRJ. Protein assembly IV is the 3D representation of the CTD as found in PDB code 2K2D. (c) RLIM E3 ligase. I is the Schematic representation of the assembly of the RLIM E3 ligase: ubiquitin (Ub) in purple, E2 ligase (E2) in dark blue, Ring domain (RING) in yellow, the disordered N-terminal end in light blue, and the substrate protein in grey. Protein assembly II is the 3D representation of the RING domain bound to the E2 ligase Ube2e2 as found in PDB code 6W9A. Protein assembly III is the 3D representation of the RING domain bound to the E2 ligase Ube2d2 as found in PDB code 6W9D. Hydrogen bonds are shown as dashed lines and zinc ions as grey spheres.