Introduction of Type II Interferon

Type II interferon Unlike the type I IFNs, which all appear to signal as monomeric cytokines, IFNγ signals as an anti-parellel homodimer. The complex through which this cytokine signals is composed of four transmembrane-spanning receptors; two chains of each of the high-affinity(IFNGR1) and low-affinity receptors (IFNGR2). The IFNγ homodimer engages directly with the two IFNGR1 chains on opposing sides of the cytokine dimer. IFNGR1 has been shown to be pre-associated with IFNGR2 and although the ligand does not engage IFNGR2 directly, ligand-induced conformational changes in both receptors have been reported. Despite the fact that both IFNGR1 and IFNGR2 are not always present together on the surface of all cells, both receptor components are required for full activity of IFNγ. For signal transduction via the JAK/STAT pathway, IFNGR1 binds to JAK1 whereas IFNGR2 binds to JAK2. Although both kinases are necessary for signal transduction, only JAK1 has been demonstrated to be required for the formation of the full IFNγ signaling complex.

Fig.Activation of phosphatidylinositol 3-kinase and protein kinase C- by the type II interferon receptor and crosstalk with the STAT-signalling pathway.
Fig.Activation of phosphatidylinositol 3-kinase and protein kinase C- by the type II interferon receptor and crosstalk with the STAT-signalling pathway.