TAB2 and TAB3 activate the NF-kappaB pathway through binding to polyubiquitin chains.

The activation of NF-kappaB and IKK requires an upstream kinase complex consisting of TAK1 and adaptor proteins such as TAB1, TAB2, or TAB3. TAK1 is in turn activated by TRAF6, a RING domain ubiquitin ligase that facilitates the synthesis of lysine 63-linked polyubiquitin chains. Here we present evidence that TAB2 ...
and TAB3 are receptors that bind preferentially to lysine 63-linked polyubiquitin chains through a highly conserved zinc finger (ZnF) domain. Mutations of the ZnF domain abolish the ability of TAB2 and TAB3 to bind polyubiquitin chains, as well as their ability to activate TAK1 and IKK. Significantly, replacement of the ZnF domain with a heterologous ubiquitin binding domain restored the ability of TAB2 and TAB3 to activate TAK1 and IKK. We also show that TAB2 binds to polyubiquitinated RIP following TNFalpha stimulation. These results indicate that polyubiquitin binding domains represent a new class of signaling domains that regulate protein kinase activity through a nonproteolytic mechanism.
Mesh Terms:
Adaptor Proteins, Signal Transducing, Amino Acid Sequence, Carrier Proteins, Cell Line, Enzyme Activation, Humans, I-kappa B Kinase, Interleukin-1, Intracellular Signaling Peptides and Proteins, MAP Kinase Kinase Kinases, Models, Biological, Molecular Sequence Data, NF-kappa B, Polyubiquitin, Protein Binding, Protein-Serine-Threonine Kinases, Proteins, Receptor-Interacting Protein Serine-Threonine Kinases, Sequence Alignment, Signal Transduction, TNF Receptor-Associated Factor 6, Tumor Necrosis Factor-alpha, Zinc Fingers
Mol. Cell
Date: Aug. 27, 2004
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