Mechanism of IκBα Binding to NF-κB Dimers*

By C. Phelps, L. L. Sengchanthalangsy, T. Huxford, G. Ghosh. Journal of Biological Chemistry, 2000

97 citations recorded by the source corpus.

X-ray crystal structures of the NF-κB·IκBα complex revealed an extensive and complex protein-protein interface involving independent structural elements present in both IκBα and NF-κB. In this study, we employ a gel electrophoretic mobility shift assay to assess and quantitate the relative contributions of the observed interactions toward overall complex binding affinity. IκBα preferentially binds to the p50/p65 heterodimer and p65 homodimer, with binding to p50 homodimer being significantly weaker. Our results indicate that the nuclear localization sequence and the region C-terminal to it of the NF-κB p65 subunit is a major contributor to NF-κB·IκBα complex formation. Additionally, there are no contacts between the corresponding nuclear localization signal tetrapeptide of p50 and IκBα. A second set of interactions involving the acidic C-terminal/PEST-like region of IκBα and the NF-κB p65 subunit N-terminal domain also contributes binding energy toward formation of the complex. This interaction is highly dynamic and nonspecific in nature, as shown by oxidative cysteine cross-linking. Phosphorylation of the C-terminal/PEST-like region by casein kinase II further enhances binding.

Subfields: Cancer Research, Immunology, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/ea3c0b13c292cb676202dcc64cebfc690f7cd6b5

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Cancer Research

1. Alexander Hoffmann
2. G. Natoli
3. S. Ghosh
4. T. Gilmore
5. M. Hayden

In Immunology

1. G. Natoli
2. Alexander Hoffmann
3. S. Ghosh
4. T. Gilmore
5. M. Hayden

In Molecular Biology

1. G. Natoli

Citations in the corpus

• Transcriptional regulation via the NF-κB signaling module (2006, background): “The affinities of physiological IkB–NF-kB complexes are much higher than that of the NF-kB dimers (pM versus nM) (Phelps et al., 2000a, b).”
• Biophysical characterization of the free IκBα ankyrin repeat domain in solution (2004, background): “I B has similar binding affinities for several NF- B partners, with a Kd of 6.0 nM for its primary cellular target p50–p65 NF- B, 16.3 nM for the p65 homodimer, and 217.6 nM affinity for the p50 homodimer (Phelps et al. 2000).”