A NOVEL MEMBER OF THE INTERFERON RECEPTOR FAMILY COMPLEMENTS FUNCTIONALITY OF THE MURINE INTERFERON-GAMMA RECEPTOR IN HUMAN-CELLS

Expression of the human interferon gamma receptor (IFN-gamma R) in mou se cells is not sufficient to confer biological responsiveness to huma n IFN-gamma and vice versa. An additional species-specific component i s required for signal transduction. We identified this cofactor by exp ression cloning in simian COS cells stably transfected with the nonfun ctional murine IFN-gamma R and a IFN-gamma-inducible reporter construc t encoding the human Tac antigen (interleukin-2 receptor alpha chain, CD25). A cDNA clone was obtained that, upon stable transfection, rende red human HEp-2 cells expressing the murine IFN-gamma R fully responsi ve to murine IFN-gamma. This cDNA encodes a novel 332 amino acid type I transmembrane protein that belongs to the IFN receptor family and th at we designate IFN-gamma R beta chain.