IFNAR2 Target Deep Dive
Cytokine Receptor Modulation
Biological Context
Interferon Alpha/Beta Receptor 2 (IFNAR2) is one of the two receptor subunits that recognize Type I interferons (IFN-α, IFN-β). Type I interferons are powerful antivirals and immune regulators — cells secrete them in response to viral infection, and signaling through the IFNAR1/IFNAR2 complex triggers hundreds of interferon-stimulated genes.
Why it matters: Modulating this pathway matters in two opposite directions. In antiviral therapy (COVID-19, hepatitis C) you want to enhance or mimic IFN signaling. In autoimmune disease (lupus, interferonopathies) you want to block it — and a well-designed IFNAR2 binder that competes with natural IFN-α would do exactly that. IFNAR2’s interface with IFN-α is one of the most thoroughly characterized cytokine-receptor interactions in the literature, which makes it an unusually well-instrumented target for de novo design.
The Goal: Design a binder that occupies the IFN-α binding face of IFNAR2 as an antagonist hypothesis. A monovalent IFNAR2 binder is not an agonist merely because of its orientation; agonism would require productive IFNAR1 recruitment and receptor geometry, followed by experimental demonstration.
Interactive Structure
The viewer below shows IFNAR2 (Chain C) in complex with IFN-α2 (Chain B) and IFNAR1 (Chain A) — the ternary signaling complex.
Non-interactive alternative: The target-specification table below describes the relevant chains and interface residues. You can also open the 3SE3 structure record or download its PDB coordinates. Manipulating the 3D viewer is optional.
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Design Mission
Create a binder that targets the IFN-α binding interface of IFNAR2 — the surface that in 3SE3 is buried by chain B.
Target Specifications
| Feature | Detail |
|---|---|
| Target Name | IFNAR2 (Interferon alpha/beta receptor 2, extracellular domain) |
| PDB ID | 3SE3 |
| Target Chain | Chain C |
| Natural partner to mimic | Chain B (IFN-α2) |
| Entry caveat | 4.0 Å structure; IFN-α2 chain B is an engineered H58Y/E59N/Q62S variant, while IFNAR2 chain C is unmutated |
| Interface-derived steering set | C44,C46,C48,C80,C100,C103 (T44, M46, K48, V80, W100, I103) |
| Structural rationale | T44/M46/K48 sample the IFN-α2 Arg33 anchor region; M46/T44/V80 and W100/I103 span two hydrophobic interaction clusters |
The six recommended residues are approximate, structure-derived contacts at the IFN-α2/IFNAR2 interface in 3SE3 and deliberately sample both interface lobes. At 4.0 Å, a distance cutoff should not be treated as atomic precision. These are interface-derived steering residues, not independently validated binder hotspots or a guarantee of binding. Verify chain and residue numbering in the exact prepared coordinates before launching a design run.
Strategy Tips
- Download PDB
3SE3. - Clean the structure: Keep Chain C only (IFNAR2). Remove IFN-α2 (B) and IFNAR1 (A).
- Define steering residues: For RFdiffusion / BindCraft, begin with
C44,C46,C48,C80,C100,C103, then test whether smaller subsets change pose diversity or interface coverage. - Consider orientation: IFN-α2 approaches IFNAR2 roughly along one face. Your binder must approach from the same general direction to avoid steric clash with IFNAR1 in a cellular context.
Reference
- Thomas, C. et al. (2011). Structural linkage between ligand discrimination and receptor activation by type I interferons. Cell 146, 621–632. doi:10.1016/j.cell.2011.06.048 — primary citation for 3SE3.
- Roisman, L.C. et al. (2001). Structure of the interferon-receptor complex determined by distance constraints from double-mutant cycles and flexible docking. PNAS 98, 13231–13236. doi:10.1073/pnas.221290398