The Human Interferon-y Receptor

The receptor for human interferon-y (IFN-y) was purified from foreskin fibroblasts. Triton X-100 extracts obtained from either intact cells or membrane preparations were passed through an immobilized interferon-? column. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of eluted fractions revealed a major band of M, = 95,000 and minor bands of M. = 80,000 and 60,000. Further purification was obtained by steric exclusion and by lectin chromatography. The purified receptor retained the ability to bind '"1-IFN-y with a Kd of 2.2 X 10"' M, a value close to that obtained with intact fibroblasts (5 X 10"' M). A complex of M. = 105,000-125,000 was visualized by immunoprecipitation of 12s1-IFN-r cross-linked to the purified receptor followed by SDS-PAGE and autoradiography. A similar complex was obtained when '2SI-IFN-y was cross-linked to intact cells. Immunization of mice with the excised SDS-PAGE band of M, = 95,000 elicited antibodies that blocked the antiviral activity of IFN-? and immunoprecipitated the cross-linked complex of '261-IFN-y and its receptor.