IFNA/B:IFNAR2:p-JAK1:STAT2:IFNAR1:p-TYK2 IFNA/B:IFNAR2:JAK1:STAT2:IFNAR1:TYK2 Activation of JAK kinases Authored: Garapati, P V, 2010-07-07 EC Number: 2.7.10 Edited: Garapati, P V, 2010-07-07 Pubmed11100472 Pubmed8702790 Pubmed9334213 Reactome Database ID Release 43909729 Reactome, http://www.reactome.org ReactomeREACT_25401 Reviewed: Abdul-Sater, AA, Schindler, C, 2010-08-17 The two chains IFNAR1 and IFNAR2 are pre-associated with the JAK kinases TYK2 and JAK1, respectively. Receptor heterodimerization brings these JAK kinases into close proximity and they are activated by reciprocal trans-phosphorylation. Tyr-1054 and Tyr-1055 within the activation loop of TYK2 sub-domain VII are critical for TYK2 activation. For JAK1 two tyrosine residues with in the KEYY motif (Tyr 1034 and Tyr 1035) of the kinase domain are thought to be transphosphorylated. has a Stoichiometric coefficient of 3