hp-IRAK1:K6-poly-Ub oligo-TRAF6:Activated TAK1 complex TAK1 is activated within the TAK1 complex Authored: Ray, KP, 2010-05-17 Edited: Jupe, S, 2010-05-17 Pubmed10702308 Pubmed14633987 Pubmed15327770 Reactome Database ID Release 43450187 Reactome, http://www.reactome.org ReactomeREACT_22176 Reviewed: Pinteaux, E, 2010-05-17 The TAK1 complex consists of the transforming growth factor-? (TGF-beta)-activated kinase (TAK1) and the TAK1-binding proteins TAB1, TAB2 and TAB3. TAK1 requires TAB1 for its kinase activity (Sakurai H et al 2000; Shibuya H et al 2000). TAB1 promotes autophosphorylation of the TAK1 kinase activation lobe, likely through an allosteric mechanism (Sakurai H et al 2000 ; Kishimoyo K et al 2000). The TAK1 complex is regulated by polyubiquitination. The TAK1 complex consists of the transforming growth factor-? (TGF- ?)-activated kinase (TAK1) and the TAK1-binding proteins TAB1, TAB2 and TAB3. TAK1 requires TAB1 for its kinase activity (Shibuya H et al 1996; Sakurai H et al 2000). TAB1 promotes autophosphorylation of the TAK1 kinase activation lobe, likely through an allosteric mechanism (Brown K et al 2005; Ono K et al 2001). The TAK1 complex is regulated by polyubiquitination. Binding of TAB2 and TAB3 to Lys63-linked polyubiquitin chains leads to the activation of TAK1 by an uncertain mechanism. Binding of multiple TAK1 complexes onto the same polyubiquitin chain may promote oligomerization of TAK1, facilitating TAK1 autophosphorylation and subsequent activation of its kinase activity (Kishimoto et al. 2000). The binding of TAB2/3 to polyubiquitinated TRAF6 may facilitate polyubiquitination of TAB2/3 by TRAF6 (Ishitani et al. 2003), which might result in conformational changes within the TAK1 complex that leads to the activation of TAK1. Another possibility is that TAB2/3 may recruit the IKK complex by binding to ubiquitinated NEMO; polyubiquitin chains may function as a scaffold for higher order signaling complexes that allow interaction between TAK1 and IKK (Kanayama et al. 2004). hp-IRAK1:K6-poly-Ub oligo-TRAF6:TAK1 complex