| IFN-a/b R2, also known as IFNAR2, is a 100 kD glycoprotein in the class II cytokine receptor family. These proteins form heterodimeric receptor complexes that transduce signals from the interferon, IL-10, and IL-28 families of cytokines. 1,2 IFN-a/b R2, in association with IFN-a/b R1, is required for mediating the antiviral, antiproliferative, and apoptotic effects of the type I interferons IFN-a and IFN-b. IFN-a/b R2 is the principal ligand binding subunit of the receptor. Ligand binding is stabilized by the subsequent association with IFN-a/b R1, resulting in the formation of a signaling ternary receptor complex. Mature human IFN-a/b R2 consists of a 217 aa extracellular domain (ECD) with two fibronectin type III repeats, a 21aa transmembrane segment, and a 251aa cytoplasmic domain. Alternate splicing generates a secreted isoform that corresponds to the ECD and a 50kD transmembrane isoform with a substituted and truncated cytoplasmic region. The short isoform is impaired in its ability to activate signaling molecules and functions as a dominant negative receptor subunit. IFN-a/b R2 is also subject to presenilin-dependent intramembrane proteolysis, resulting in the liberation of nearly the entire ECD as well as the cytoplasmic domain which migrates to the nucleus and can inhibit gene transcription. High concentrations of soluble IFN-a/b R2 bind and neutralize IFN-a and IFN-b, while lower concentrations prolong the antiviral activity of circulating IFN-b but not IFN-a. Human but not mouse IFN-a/b R2 constitutively associates with STAT4, which may account for species specific differences observed in type I interferon responses. 12 Within the ECD, human IFN-a/b R2 shares 63%, 60%, and 48% aa sequence identity with bovine, mouse, and ovine IFN-a/b R2. Source: Recombinant corresponding to human CD33 (aa 1-16), human IFN-a/b R2 (aa27-243), IEGRMD linker and human IgG (aa100-330) expressed in mouse NSO myeloma cells Molecular Mass: The recombinant human IFN-a/b R2/Fc is a disulfide-linked homodimeric protein. Based on N- terminal amino acid sequencing, the recombinant human IFN-a/b R2/Fc starts at Ile 27. Each monomer has a calculated molecular mass of approximately 51.3 kD. As a result of glycosylation, recombinant human IFN-a/b R2/Fc migrates as an approximately 71-76kD protein in a SDS-PAGE under reducing conditions. Activity: Measured by its ability to enhance rhIFN-b mediated antiviral activity (McKenna, S.D., et al., 2004, J. Interferon Cytokine Res. 24:119-129). The ED 50 for this effect is typically 6-30ng/mL in the presence of 0.6ng/mL rhIFN-b. Storage and Stability: Lyophilized powder may be stored at -20C. Stable for 12 months at -20C. Reconstitute with sterile PBS, 0.1% HSA or BSA. Aliquot to avoid repeated freezing and thawing. Store at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer. |
