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Updated: Sep 25, 2025

Production, Crystallization, and Structure Determination of the IKK-binding Domain of NEMO
Published on: December 28, 2019
Liquid phase separation of NEMO induced by polyubiquitin chains activates NF-κB
Mingjian Du1, Chee-Kwee Ea1, Yan Fang1
1Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA; Center for Inflammation Research, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA.
None:
The NF-κB essential modulator (NEMO) is a regulatory subunit of the IκB kinase (IKK) complex that phosphorylates the NF-κB inhibitors IκBs. NEMO mediates IKK activation by binding to polyubiquitin chains (polyUb). Here, we show that Lys63(K63)-linked or linear polyUb binding to NEMO robustly induced the formation of liquid-like droplets in which IKK was activated. This liquid phase separation of NEMO was driven by multivalent interactions between NEMO and polyUb. Both the NEMO ubiquitin-binding (NUB) domain and the zinc-finger (ZF) domain of NEMO mediated binding to polyUb and contributed to NEMO phase separation and IKK activation in cells. Moreover, NEMO mutations associated with human immunodeficiency impaired its phase separation. These results demonstrate that polyUb activates IKK and NF-κB signaling by promoting the phase separation of NEMO.
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