Tyrosine kinase 2 TYK2(X54637:9606) is a member of IFNα/β signaling that belongs to the Janus kinase (JAK) family. Activation of TYK2(X54637:9606) by IFNα/β stimulation leads to a series of phosphorylation events, causing the formation of IFN stimulated gene factor 3 (ISGF3) complexes that consist of STAT1(M97935:9606), STAT2(M97934:9606) and IFN regulatory factor 9 IRF9(M87503:9606). Subsequently, ISGF3 translocates to the nucleus and binds to IFN stimulated response elements (IRF/ISRE), which in turn activates transcription of several hundred IFN-responsive genes.
Several viruses have evolved mechanisms to inhibit TYK2(X54637:9606) activity and prevent the subsequent activation of downstream partners STAT1(M97935:9606) and STAT2(M97934:9606). The Epstein-Barr virus LMP-1(P03230) protein interacts with TYK2(X54637:9606) and prevents its phosphorylation. Human papillomavirus E6(P03126) also interacts with and impair TYK2(X54637:9606) activation.