Expression cloning of the murine interferon gamma receptor cDNA

A cDNA encoding a receptor for murine interferon gamma (IFN-gamma) was isolated from an expression library made from murine thymocytes. The clone was identified by transfecting the library into monkey COS cells and probing the transfected monolayer with radiolabeled murine IFN-gamma. Cells expressing the receptor were identified by autoradiography and plasmids encoding the receptor were directly rescued from those cells producing a positive signal. A partial cDNA so obtained was used to isolate a full-length cDNA from mouse L929 cells by conventional means. When this cDNA was expressed in COS cells it produced a specific binding site for murine IFN-gamma with an affinity constant similar to that of the receptor found on L929 cells. The predicted amino acid sequence of the murine IFN-gamma receptor shows homology to that previously reported for the human IFN-gamma receptor. However, although the two proteins are clearly related, they show less than 60% identity in both the putative extracellular domain and the intracellular domain.