Within the TAK1 complex (TAK1 plus TAB1 and TAB2/3) activated TAK1 phosphorylates IKKB, MAPK kinase 6 (MKK6) and other MAPKs to activate the NFkappaB and MAPK signaling pathways. TAB2 within the TAK1 complex can be linked to polyubiquitinated TRAF6; current models of IL-1 signaling suggest that the TAK1 complex is linked to TRAF6, itself complexed with polyubiquitinated IRAK1 which is linked via NEMO to the IKK complex. The TAK1 complex is also essential for NOD signaling; NOD receptors bind RIP2 which recruits the TAK1 complex (Hasegawa et al. 2008).
MAP kinase kinase kinase activity of TAK1 complex [cytosol]