BOVINE TYPE-I INTERFERON RECEPTOR PROTEIN BOIFNAR-1 HAS HIGH-AFFINITYAND BROAD-SPECIFICITY FOR HUMAN TYPE-I INTERFERONS

The type I interferon receptor (IFNAR(1)) is composed of two transmemb rane polypeptides, IFNAR-1 and IFNAR-2. Human IFNAR-1 has low intrinsi c affinity for IFNs, but enhances the affinity for IFNs of the complex over that of HuIFNAR-2 alone, and modulates the ligand specificity, B ovine cells respond to human alpha interferons, The bovine homologue o f HuIFNAR-1, BoIFNAR-1, when expressed in heterologous cells, confers high-affinity binding and broad specificity for human type I IFNs. A s oluble fusion protein of the ectodomain of BoIFNAR-1 and an immunoglob ulin Fc domain was produced, In contrast to HuIFNAR-1, this protein co mpetes strongly with human cells for IFN binding, and directly binds a wide spectrum of human type I IFNs, including diverse IFN-alpha s, IF N-beta and IFN-omega, with moderate to high affinity, This accounts fo r much of the specificity for human IFNs possessed by bovine cells, wi th several exceptions, The BoIFNAR-1 ectodomain, in contrast to HuIFNA R-1, may be useful for studies of binary and ternary complexes with IF Ns and IFNAR-2, and for purification, assay and biological neutralizat ion protocols, (C) 1998 Federation of European Biochemical Societies.