CDw119 is a 90 kD immunoglobulin superfamily member, also known as IFN-gammaRalpha chain. It is a class II cytokine receptor family member that serves as a IFN-gamma-binding chain associated with the IFN-gamma beta chain also known as AF-1. In addition to ligand binding, CDw119 participates in ligand trafficking. CDw119 is expressed on T and B cells, NK cells, fibroblasts, endothelial, and epithelial cells. Binding of IFN-gamma induces receptor dimerization, internalization, Jak1 and Jak2 protein kinase activation and, ultimately, STAT1 activation. IFN-gamma initiates and regulates a variety of immune responses.