c-IAP1 and UbcH5 promote K11-linked polyubiquitination of RIP1 in TNF signalling

EMBO J. 2010 Dec 15;29(24):4198-209. doi: 10.1038/emboj.2010.300. Epub 2010 Nov 26.


Ubiquitin ligases are critical components of the ubiquitination process that determine substrate specificity and, in collaboration with E2 ubiquitin-conjugating enzymes, regulate the nature of polyubiquitin chains assembled on their substrates. Cellular inhibitor of apoptosis (c-IAP1 and c-IAP2) proteins are recruited to TNFR1-associated signalling complexes where they regulate receptor-stimulated NF-κB activation through their RING domain ubiquitin ligase activity. Using a directed yeast two-hybrid screen, we found several novel and previously identified E2 partners of IAP RING domains. Among these, the UbcH5 family of E2 enzymes are critical regulators of the stability of c-IAP1 protein following destabilizing stimuli such as TWEAK or CD40 signalling or IAP antagonists. We demonstrate that c-IAP1 and UbcH5 family promote K11-linked polyubiquitination of receptor-interacting protein 1 (RIP1) in vitro and in vivo. We further show that TNFα-stimulated NF-κB activation involves endogenous K11-linked ubiquitination of RIP1 within the TNFR1 signalling complex that is c-IAP1 and UbcH5 dependent. Lastly, NF-κB essential modifier efficiently binds K11-linked ubiquitin chains, suggesting that this ubiquitin linkage may have a signalling role in the activation of proliferative cellular pathways.

MeSH terms

  • Cell Line
  • Humans
  • Inhibitor of Apoptosis Proteins / metabolism*
  • NF-kappa B / metabolism
  • Nuclear Pore Complex Proteins / metabolism*
  • Protein Binding
  • RNA-Binding Proteins / metabolism*
  • Tumor Necrosis Factor-alpha / metabolism
  • Two-Hybrid System Techniques
  • Ubiquitin-Conjugating Enzymes / metabolism*
  • Ubiquitination


  • AGFG1 protein, human
  • Inhibitor of Apoptosis Proteins
  • NF-kappa B
  • Nuclear Pore Complex Proteins
  • RNA-Binding Proteins
  • Tumor Necrosis Factor-alpha
  • Ubiquitin-Conjugating Enzymes