RBX1-09

• Submission order: 9
• Score rank: 9
• Format: Mini-protein
• Primary state: 8Q7R functional state
• Design method: BindCraft backbone plus ProteinMPNN redesign
• Description: This functional-state backup was kept because it preserves the E2-facing route with a cleaner fold-quality profile than the denser lead, giving that lane a more developable alternative. The working model targets a functional RBX1 conformation related to the E2-facing interface in the 8Q7R functional state, and follow-up refolds recovered compatible placements in the 4F52 main-face conformation and the 3RTR transfer-related conformation. The clearest quantitative positives here are a modeled contact patch built around 3 residues on the binder side, a patch that currently touches 2 residues on RBX1, localized RBX1 surface coverage of 0.167, high interface confidence at 0.914, strong developability at 0.969, and a composite ranking score of 5.8770. Novelty support is acceptable: the UniRef50 30-aa sliding-window screen is clear; no strong competing interaction is flagged in the off-target screen; the main caution is that the modeled interface remains relatively narrow, even though the fold-level signal is encouraging; the full project rationale and design workflow are documented at https://github.com/tuna010101/RBX1-Binder-Design-Portfolio