Human Interferon-α Receptor: Identification of the Region Involved in Binding to Interferon-αB

Three polypeptides comprising amino acids 1–102, 93–260, and 261–410 of the extracellular domain of the human interferon-α receptor HuIFN-αR (Uzé, G., Lutfalla, G., and Gresser, I. Cell 1990; 60:225–234) have been expressed in Escherichia coli. The polypeptides were sequestered within bacterial inclusion bodies. Inclusion body material was solubilized by 8 M urea, and the polypeptides were purified by gel filtration or histidine tag-based affinity chromatography. Overall recovery of each purified and refolded polypeptide was approximately 0.5–0.8 mg/liter of cell culture. The polypeptides migrated as homogeneous monomers of 12 kDa, 22 kDa, and 17 kDa, respectively on reduced sodium dodecylsulfate polyacrylamide gel electrophoresis. The polypeptide fragments corresponding to amino acids 1–102, and 93–260 of the extracellular domain of HuIFN-αR lacked the ability to bind to IFN-αB and to inhibit its biologic activities. The polypeptide fragment corresponding to amino acids 261–410 of the receptor molecule inhibited the antiproliferative activity of IFN-αB and competed with the Daudi cell surface receptor for binding to this IFN-α species.