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. Author manuscript; available in PMC: 2010 Mar 1.
Published in final edited form as: Immunol Rev. 2009 Mar;228(1):273–287. doi: 10.1111/j.1600-065X.2008.00754.x

Fig. 1. Schematic structure of Jaks.

Fig. 1

The Jak family comprises four structurally related kinases: Jak1, Jak2, Jak3, and Tyk2. Seven Jak homology regions (JH) containing the catalytically active kinase domain (JH1), the enzymatically inactive pseudokinase domain (JH2), the SH2 domain (JH3, JH4), and a FERM domain (JH6, JH7) form the Jak protein. The FERM domain mediates Jak binding to the transmembrane cytokine receptor and regulates kinase activity.