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Jak1 |
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| The Janus family of non-receptor tyrosine kinases (JAK1, JAK2, JAK3 and tyrosine kinase 2) transduces signals downstream of type I and II cytokine receptors via signal transducers and activators of transcription (STATs).
JAK contain seven JH domains organized into four regions; kinase (JH1), pseudo-kinase (JH2), FERM(the N-terminal JH7, JH6, JH5 and part of JH4) and SH2-like (JH3 and part of JH4).
Upon cytokine receptor activation, Jak proteins become autophosphorylated and phosphorylate their associated receptors to provide multiple binding sites for signaling proteins.
Expression is ubiquitous for JAK1, JAK2 and TYK2 but restricted to hematopoietic cells for JAK3.
Jak1 is a crucial kinase in signal transduction of cytokines including IFNs
as well as IL-6- and IL-2-type cytokines. Activation of Jak1 occurs via phosphorylation at tyrosine residues, Y1022 and Y1023 within the kinase domain. Jak1 is required for the activation of STAT1 and STAT2 in response to interferon. |
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1) Cheng H et al., 2008, Mol Cell Biol 28(7):2271–2282
2) Hann S et al., 2008, J Immunology 180:998-1007
3) Schindler CW, 2002, J Clin Invest 109:1133–1137
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