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Nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha
Crystallographic structure (PDB: 1NFI​) of I?B? (magenta) complexed with a homodimer of the NF-?B heterodimeric protein (p65 - cyan and p50 - green).
Available structures
PDB Ortholog search: PDBe, RCSB
External IDs OMIM164008 MGI104741 HomoloGene7863 ChEMBL: 2898 GeneCards: NFKBIA Gene
RNA expression pattern
PBB GE NFKBIA 201502 s at tn.png
More reference expression data
Species Human Mouse
Entrez 4792 18035
Ensembl ENSG00000100906 ENSMUSG00000021025
UniProt P25963 Q9Z1E3
RefSeq (mRNA) NM_020529 NM_010907
RefSeq (protein) NP_065390 NP_035037
Location (UCSC) Chr 14:
35.4 – 35.4 Mb
Chr 12:
55.49 – 55.49 Mb
PubMed search [1] [2]

IκBα (nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha) is one member of a family of cellular proteins that function to inhibit the NF-κB transcription factor. IκBα inhibits NF-κB by masking the nuclear localization signals (NLS) of NF-κB proteins and keeping them sequestered in an inactive state in the cytoplasm.[1] In addition, IκBα blocks the ability of NF-κB transcription factors to bind to DNA, which is required for NF-κB's proper functioning.[2]

Disease linkage[edit]

The gene encoding the IκBα protein is mutated in some Hodgkin's lymphoma cells; such mutations inactivate the IκBα protein, thus causing NF-κB to be chronically active in the lymphoma tumor cells and this activity contributes to the malignant state of these tumor cells.[3]


IκBα has been shown to interact with:


  1. ^ Jacobs MD, Harrison SC (1998). "Structure of an IkappaBalpha/NF-kappaB complex". Cell 95 (6): 749–58. doi:10.1016/S0092-8674(00)81698-0. PMID 9865693. 
  2. ^ Verma IM, Stevenson JK, Schwarz EM, Van Antwerp D, Miyamoto S (1995). "Rel/NF-kappa B/I kappa B family: intimate tales of association and dissociation". Genes Dev. 9 (22): 2723–35. doi:10.1101/gad.9.22.2723. PMID 7590248. 
  3. ^ Cabannes E, Khan G, Aillet F, Jarrett RF, Hay RT (1999). "Mutations in the IkBa gene in Hodgkin's disease suggest a tumour suppressor role for IkappaBalpha". Oncogene 18 (20): 3063–70. doi:10.1038/sj.onc.1202893. PMID 10340377. 
  4. ^ Suzuki H, Chiba T, Suzuki T, Fujita T, Ikenoue T, Omata M, Furuichi K, Shikama H, Tanaka K (January 2000). "Homodimer of two F-box proteins betaTrCP1 or betaTrCP2 binds to IkappaBalpha for signal-dependent ubiquitination". J. Biol. Chem. 275 (4): 2877–84. doi:10.1074/jbc.275.4.2877. PMID 10644755. 
  5. ^ a b Spencer E, Jiang J, Chen ZJ (February 1999). "Signal-induced ubiquitination of IkappaBalpha by the F-box protein Slimb/beta-TrCP". Genes Dev. 13 (3): 284–94. doi:10.1101/gad.13.3.284. PMC 316434. PMID 9990853. 
  6. ^ "Molecular Interaction Database". 
  7. ^ a b c Cohen L, Henzel WJ, Baeuerle PA (September 1998). "IKAP is a scaffold protein of the IkappaB kinase complex". Nature 395 (6699): 292–6. doi:10.1038/26254. PMID 9751059. 
  8. ^ a b Woronicz JD, Gao X, Cao Z, Rothe M, Goeddel DV (October 1997). "IkappaB kinase-beta: NF-kappaB activation and complex formation with IkappaB kinase-alpha and NIK". Science 278 (5339): 866–9. doi:10.1126/science.278.5339.866. PMID 9346485. 
  9. ^ DiDonato JA, Hayakawa M, Rothwarf DM, Zandi E, Karin M (August 1997). "A cytokine-responsive IkappaB kinase that activates the transcription factor NF-kappaB". Nature 388 (6642): 548–54. doi:10.1038/41493. PMID 9252186. 
  10. ^ Ninomiya-Tsuji J, Kishimoto K, Hiyama A, Inoue J, Cao Z, Matsumoto K (March 1999). "The kinase TAK1 can activate the NIK-I kappaB as well as the MAP kinase cascade in the IL-1 signalling pathway". Nature 398 (6724): 252–6. doi:10.1038/18465. PMID 10094049. 
  11. ^ Crépieux P, Kwon H, Leclerc N, Spencer W, Richard S, Lin R, Hiscott J (December 1997). "I kappaB alpha physically interacts with a cytoskeleton-associated protein through its signal response domain". Mol. Cell. Biol. 17 (12): 7375–85. PMC 232593. PMID 9372968. 
  12. ^ Prigent M, Barlat I, Langen H, Dargemont C (November 2000). "IkappaBalpha and IkappaBalpha /NF-kappa B complexes are retained in the cytoplasm through interaction with a novel partner, RasGAP SH3-binding protein 2". J. Biol. Chem. 275 (46): 36441–9. doi:10.1074/jbc.M004751200. PMID 10969074. 
  13. ^ a b c Hay DC, Kemp GD, Dargemont C, Hay RT (May 2001). "Interaction between hnRNPA1 and IkappaBalpha is required for maximal activation of NF-kappaB-dependent transcription". Mol. Cell. Biol. 21 (10): 3482–90. doi:10.1128/MCB.21.10.3482-3490.2001. PMC 100270. PMID 11313474. 
  14. ^ Mercurio F, Murray BW, Shevchenko A, Bennett BL, Young DB, Li JW, Pascual G, Motiwala A, Zhu H, Mann M, Manning AM (February 1999). "IkappaB kinase (IKK)-associated protein 1, a common component of the heterogeneous IKK complex". Mol. Cell. Biol. 19 (2): 1526–38. PMC 116081. PMID 9891086. 
  15. ^ a b Malek S, Huxford T, Ghosh G (September 1998). "Ikappa Balpha functions through direct contacts with the nuclear localization signals and the DNA binding sequences of NF-kappaB". J. Biol. Chem. 273 (39): 25427–35. doi:10.1074/jbc.273.39.25427. PMID 9738011. 
  16. ^ Chang NS (March 2002). "The non-ankyrin C terminus of Ikappa Balpha physically interacts with p53 in vivo and dissociates in response to apoptotic stress, hypoxia, DNA damage, and transforming growth factor-beta 1-mediated growth suppression". J. Biol. Chem. 277 (12): 10323–31. doi:10.1074/jbc.M106607200. PMID 11799106. 
  17. ^ Fischle W, Verdin E, Greene WC (August 2001). "Duration of nuclear NF-kappaB action regulated by reversible acetylation". Science 293 (5535): 1653–7. doi:10.1126/science.1062374. PMID 11533489. 
  18. ^ Kiernan R, Brès V, Ng RW, Coudart MP, El Messaoudi S, Sardet C, Jin DY, Emiliani S, Benkirane M (January 2003). "Post-activation turn-off of NF-kappa B-dependent transcription is regulated by acetylation of p65". J. Biol. Chem. 278 (4): 2758–66. doi:10.1074/jbc.M209572200. PMID 12419806. 
  19. ^ Hansen SK, Baeuerle PA, Blasi F (April 1994). "Purification, reconstitution, and I kappa B association of the c-Rel-p65 (RelA) complex, a strong activator of transcription". Mol. Cell. Biol. 14 (4): 2593–603. doi:10.1128/mcb.14.4.2593. PMC 358627. PMID 8139561. 
  20. ^ Schouten GJ, Vertegaal AC, Whiteside ST, Israël A, Toebes M, Dorsman JC, van der Eb AJ, Zantema A (June 1997). "IkappaB alpha is a target for the mitogen-activated 90 kDa ribosomal S6 kinase". EMBO J. 16 (11): 3133–44. doi:10.1093/emboj/16.11.3133. PMC 1169932. PMID 9214631. 
  21. ^ Guo D, Li M, Zhang Y, Yang P, Eckenrode S, Hopkins D, Zheng W, Purohit S, Podolsky RH, Muir A, Wang J, Dong Z, Brusko T, Atkinson M, Pozzilli P, Zeidler A, Raffel LJ, Jacob CO, Park Y, Serrano-Rios M, Larrad MT, Zhang Z, Garchon HJ, Bach JF, Rotter JI, She JX, Wang CY (August 2004). "A functional variant of SUMO4, a new I kappa B alpha modifier, is associated with type 1 diabetes". Nat. Genet. 36 (8): 837–41. doi:10.1038/ng1391. PMID 15247916. 
  22. ^ Dai RM, Chen E, Longo DL, Gorbea CM, Li CC (February 1998). "Involvement of valosin-containing protein, an ATPase Co-purified with IkappaBalpha and 26 S proteasome, in ubiquitin-proteasome-mediated degradation of IkappaBalpha". J. Biol. Chem. 273 (6): 3562–73. doi:10.1074/jbc.273.6.3562. PMID 9452483. 

Further reading[edit]

External links[edit]