Fig. 8.

Conserved ligand interactions with the RT loop. (a) Superposition of the p73–ASPP2 complex with a Cbl-b peptide bound to the SH3 domains of CIN85 (PDB ID 2BZ8).⁴⁵ The surface of one CIN85 SH3 domain is shown in gray, and the Cbl-b and p73 chains are shown in red and green, respectively. The p73 L3 loop is structurally distinct from the extended proline-rich sequences of most SH3 ligands. (b) Although the binding mode of p73 is distinct from extended SH3 ligand interactions, several features are conserved. These include the critical arginine interaction with the RT loop and a backbone hydrogen bond to ASPP2 W1097.