page_title: Interferon-alpha/beta receptor
section_title: IFNAR2
hierarchical_section_title: Interferon-alpha/beta receptor / Structure / Subunits / IFNAR2
caption_attribution_description: English: IFNAR binding schematic
context_page_description: The interferon-α/β receptor is a virtually ubiquitous membrane receptor which binds endogenous type I interferon cytokines. Endogenous human type I IFNs include many subtypes, such as interferons-α, -β, -ε, -κ, -ω, and -ζ.
context_section_description: IFNAR2 is the high affinity subunit, originally cloned in 1994, composed of two FNII-like subdomains, termed D1 and D2. Type I IFNs bind D1 and D2 with a typical binding affinity between 0.4–5nM; IFNβ binds at a slightly lower affinity (0.1nM). Type I IFNs have a binding association rate of 10⁻⁶–10⁻⁷M/s with a variable dissociation rate that determines type I IFN subtype affinity for IFNAR2.
  IFNAR2 is expressed as three isoforms due to alternative splicing, exon skipping, and multiple polyadenylation sites; IFNAR2a (a soluble form lacking the TM domain), IFNAR2b (a soluble form lacking the cytoplasmic domain), and IFNAR2c (the membrane bound, signaling-competent form). The cytoplasmic domain of IFNAR2c associates with JAK1.
caption: This modified schematic shows each subunit independently binding the type I IFN ligand and recruiting the corresponding subunit.[9] The IFNAR1 and IFNAR2 binding motifs on type I IFNs are approximately 180 degrees from each other.[9] IFNAR is composed of two subunits, IFNAR1 and IFNAR2. Each IFNAR subunit contains an N-terminal ligand binding domain, a transmembrane domain, and a C-terminal intracellular tail.[9]  IFNAR1 is the low affinity subunit, with four N-terminal subdomains. Binding to type I IFN is mediated by subdomains SD1, SD2 and SD3. IFNAR1's C-terminal tail interacts with Tyk2.[7] IFNAR2 is the high affinity subunit, composed of two N-terminal subdomains. Binding to type I IFN is mediated by D1 and D2. IFNAR2's C-terminal tail interacts with JAK1.[7]
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