I kappa B proteins: structure, function and regulation

Semin Cancer Biol. 1997 Apr;8(2):75-82. doi: 10.1006/scbi.1997.0058.


The Rel/NF-kappa B transcription factors represent the paradigm of regulation of transcriptional activation through sub-cellular localization. In unstimulated cells, NK-kappa B exists in an inactive state in the cytoplasm complexed to the inhibitory I kappa B molecules. Upon stimulation, I kappa B is rapidly degraded, freeing NF-kappa B to translocate to the nucleus and to activate the expression of its target genes. In this chapter, we will summarize what is known about the structure of I kappa B molecules, their functions, the mechanisms of I kappa B degradation, and the most common upstream signaling pathway (that is, serine phosphorylation) that leads to I kappa B degradation. Finally, we will discuss alternative mechanisms for induction of NF-kappa B through regulation of I kappa B activity.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Humans
  • NF-kappa B / physiology*
  • Phosphorylation
  • Phosphotransferases
  • Protein Conformation
  • Proto-Oncogene Proteins* / chemistry
  • Proto-Oncogene Proteins* / genetics
  • Proto-Oncogene Proteins* / physiology
  • Signal Transduction
  • Structure-Activity Relationship
  • Transcription Factor RelB
  • Transcription Factors*


  • NF-kappa B
  • Proto-Oncogene Proteins
  • RELB protein, human
  • Transcription Factors
  • Transcription Factor RelB
  • Phosphotransferases