Figure 6. Crystal structure of RNF125^stop129; models of UbcH5a interactions.

(A) Ribbon diagram of the RNF125^stop129 structure with the RING domain in green, the C2HC ZnF in blue, the linker region L1 in grey and Li2^120-128 in pink. A 90° rotated view is also shown. (B) Overlays of the RNF125^stop129 structure (orange) with eight X-ray structures of RING domains (yellow) co-crystallized with UbcH5 E2 proteins (blue) or with a UbcH5a-Ub conjugate (4AP4). Ubiquitin is in purple. Structures from PDB were: 4QPL (RNF146/UbchH5a); 2YHO (Mylip/UbcH5a); 4V3K (RNF38/UbcH5b); 4AUQ (Birc7/UbcH5b); 4A4C (Cbl/UbcH5b); 3EB6 (IAP/ UbcH5b); 3RPG (Bmi/UbcH5c). Some PDB files were altered to depict the RING domain and E2 only. (C) Model of RNF125^stop129 in association with UbcH5a, generated by overlaying RNF125^stop129 with RNF146 in PDB 4QPL. The CSPs observed in the NMR experiments of Fig. 4 (¹⁵N-UbcH5a/RNF125^{start31/stop129} at 1:0.9) and Fig. 5 (¹⁵N-RNF125^stop129/Ubch5a at 1:2) are highlighted on RNF125^stop129 (yellow-orange) and UbcH5a (cyan-blue). Residues that broadened beyond detection are in red. A 180° rotated view is also shown.