Figure 1.

Contributions of IFNAR1 SD1–4 to IFN-β binding. A, crystal structure of IFNAR1 (blue) in complex with IFN-β (yellow). Shown are relative percentage contributions of each domain of IFNAR1 to the overall IFN-β binding interface (crystal structure of the IFN-β-IFNAR1 complex from de Weerd et al. (11); PDB code 3WCY). B, the helices of IFN-β (A–E) and the IFNAR1 subdomains (SD1–4) are indicated. The positions of Tyr²⁴⁰ and Tyr²⁷⁴ are indicated with dark blue spheres. C, close-up view of the binding of Tyr²⁴⁰ and Tyr²⁷⁴ (blue sticks) to residues on the B and C helices of IFN-β (yellow sticks). D, diagrammatic representation of IFNAR1-ECD truncation variants generated in this study. E, native PAGE (10% v/v) analysis of IFNAR1-ECD, IFNAR1-SD123, and IFNAR1-SD12 alone and with IFN-β. These interactions were carried out in triplicate.