A new member of the Iκb protein family, IκBε, inhibits RelA (p65)- mediated NF-κB transcription

Zhen Li, Gary J. Nabel

Research output: Contribution to journalArticlepeer-review

89 Scopus citations


A novel member of the IκB family has been identified as a protein that associated with the p50 subunit of NF-κB in a yeast two-hybrid screen. Similar to previously known IκB proteins, this member, IκBε, has six consecutive ankyrin repeats. IκBε mRNA is widely expressed in different human tissues, with highest levels in spleen, testis, and lung. IκBε interacts with different NF-κB proteins, including p65 (RelA), c-Rel, p50, and p52, in vitro and in viva and inhibits the DNA-binding activity of both p50-p65 and p50-c-Rel complexes effectively. Endogenous and transfected NF- κB (RelA-dependent) transcriptional activation is inhibited by IκBε. IκBε mRNA is expressed at different levels in specific cell types and is synthesized constitutively in transformed B-cell lines. It also displays differential induction in response to tumor necrosis factor alpha, interleukin-1, or phorbol ester stimulation compared to IκBα in non-B-cell lines. Therefore, IκBε represents a novel IκB family member which provides an alternative mechanism for regulation of NF-κB-dependent transcription.

Original languageEnglish (US)
Pages (from-to)6184-6190
Number of pages7
JournalMolecular and Cellular Biology
Issue number10
StatePublished - Oct 1997
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Cell Biology


Dive into the research topics of 'A new member of the Iκb protein family, IκBε, inhibits RelA (p65)- mediated NF-κB transcription'. Together they form a unique fingerprint.

Cite this