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IKK-1 and IKK-2: cytokine-activated IkappaB kinases essential for NF-kappaB activation.

Activation of the transcription factor nuclear factor kappa B (NF-kappaB) is controlled by sequential phosphorylation, ubiquitination, and degradation of its inhibitory subunit IkappaB. A large multiprotein complex, the IkappaB kinase (IKK) signalsome, was purified from HeLa cells and found to contain a cytokine-inducible IkappaB kinase activity that phosphorylates IkappaB-alpha and IkappaB-beta. Two components of the IKK signalsome, IKK-1 and IKK-2, were identified as closely related protein serine kinases containing leucine zipper and helix-loop-helix protein interaction motifs. Mutant versions of IKK-2 had pronounced effects on RelA nuclear translocation and NF-kappaB-dependent reporter activity, consistent with a critical role for the IKK kinases in the NF-kappaB signaling pathway.

Pubmed ID: 9346484


  • Mercurio F
  • Zhu H
  • Murray BW
  • Shevchenko A
  • Bennett BL
  • Li J
  • Young DB
  • Barbosa M
  • Mann M
  • Manning A
  • Rao A


Science (New York, N.Y.)

Publication Data

October 31, 1997

Associated Grants


Mesh Terms

  • Cell Cycle Proteins
  • Cloning, Molecular
  • Dual Specificity Phosphatase 1
  • Enzyme Activation
  • HeLa Cells
  • Helix-Loop-Helix Motifs
  • Humans
  • I-kappa B Kinase
  • Immediate-Early Proteins
  • Leucine Zippers
  • Molecular Sequence Data
  • NF-kappa B
  • Phosphoprotein Phosphatases
  • Phosphorylation
  • Protein Phosphatase 1
  • Protein Tyrosine Phosphatases
  • Protein-Serine-Threonine Kinases
  • Sequence Homology, Amino Acid
  • Substrate Specificity