IFN-α/β R1, also known as IFNAR1, belongs to the class II cytokine receptor family of proteins. Class II cytokine receptors form heterodimeric receptor complexes that mediate class II cytokine signals. Subunits of the different receptor complexes are shared and serve multiple functions. IFN-α/β R1, in association with IFN-α/β R2, is required for propagating antiviral signal transduction triggered by IFN-α and IFN-β. IFN-α/β R1 interacts very weakly or not at all with type 1 interferons and does not stably interact with IFN-α/β R2. Ligands associate with IFN-α/β R2, and this complex subsequently forms a stable ternary assembly with IFN-α/β R1. IFN-α/β R1 also associates with IFN-γ R2 even in the absence of IFN-γ stimulation. Human-α/β R1 contains a nuclear localization signal in its extracellular domain that is required for receptor translocation to the nucleus following interaction with ligand.