Interferons (IFNs) can be devided in three classes, Type I, II and III. Type I IFNs are created when the cell surface or specific receptors recognize microbial products; these are structural homologues of one another which bind the same receptor. Binding to this receptor leads to an activation of kinases which regulate the phosphorylation and therefore activation of some STAT proteins (see PW for details).
There is only 1 Type II interferon, INF-gamma, consisting of two subunits (R1 and R2), which associate with Jak 1 and 2, respectively. Activation of Jak1 and Jak2 leads to phosphorylation of STAT1, which ultimately binds to IFN-gamma-activated sequence (GAS) elements, regulating the transcription of genes.
Type III interferons are considered a protein family of 4, which bind to a different receptor compared to Type I interferons, however they trigger the same STAT1+2 phosphorylation reactions as TypeI IFNs.e65d7eaebd7e30936491PubMedDecoding type I and III interferon signalling during viral infection.Nat Microbiol2019Mesev EVLeDesma RAPloss Atype II interferon signaling pathwayPW:0000896Pathway Ontology21372217PubMedDirect effects of type I interferons on cells of the immune system.Clin Cancer Res2011Hervas-Stubbs SPerez-Gracia JLRouzaut ASanmamed MFLe Bon AMelero Isignaling pathwayPW:0000003Pathway Ontology15864272PubMedMechanisms of type-I- and type-II-interferon-mediated signalling.Nat Rev Immunol2005Platanias LCtype I interferon signaling pathwayPW:0000895Pathway Ontology