The interferon gamma (IFN-γ) receptor: A paradigm for the multichain cytokine receptor

With the purification and cloning of the interferon gamma (IFN-γ) receptor chains the mechanism of IFN-γ action and the resultant signal transduction events were delineated in remarkable detail. The interferon gamma (IFN-γ) receptor complex consists of two chains: IFN-γR1, the ligand- binding chain, and IFN-γR2, the accessory chain. Binding of IFN-γ causes oligomerization of the two IFN-γ receptor subunits, IFN-γR1 and IFN-γR2, which initiates the signal transduction events: activation of Jak1 and Jak2 receptor associated protein tyrosine kinases, phosphorylation of the IFN- γR1 intracellular domain on Tyr⁴⁴⁰ followed by phosphorylation and activation of Stat1α, the latent transcriptional factor. With all these steps established, the IFN-γ receptor complex has provided the basic model for understanding the receptors for other members of the family of class II cytokine receptors.