A new member of the I kappaB protein family, I kappaB epsilon, inhibits RelA (p65)-mediated NF-kappaB transcription.
A novel member of the I kappaB family has been identified as a protein that associated with the p50 subunit of NF-kappaB in a yeast two-hybrid screen. Similar to previously known I kappaB proteins, this member, I kappaB epsilon, has six consecutive ankyrin repeats. I kappaB epsilon mRNA is widely expressed in different human tissues, with highest levels in spleen, testis, and lung. I kappaB epsilon interacts with different NF-kappaB proteins, including p65 (RelA), c-Rel, p50, and p52, in vitro and in vivo and inhibits the DNA-binding activity of both p50-p65 and p50-c-Rel complexes effectively. Endogenous and transfected NF-kappaB (RelA-dependent) transcriptional activation is inhibited by I kappaB epsilon. I kappaB epsilon 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 I kappaB alpha in non-B-cell lines. Therefore, I kappaB epsilon represents a novel I kappaB family member which provides an alternative mechanism for regulation of NF-kappaB-dependent transcription.
Pubmed ID: 9315679 RIS Download
Amino Acid Sequence | Ankyrin Repeat | B-Lymphocytes | Cell Line | Cloning, Molecular | DNA | DNA, Complementary | Epithelial Cells | Gene Expression Regulation | Humans | I-kappa B Proteins | Interleukin-1 | Kidney | Molecular Sequence Data | NF-kappa B | NF-kappa B p50 Subunit | NF-kappa B p52 Subunit | Organ Specificity | Protein Binding | Proto-Oncogene Proteins | Proto-Oncogene Proteins c-rel | RNA, Messenger | T-Lymphocytes | Tetradecanoylphorbol Acetate | Transcription Factor RelA | Transcriptional Activation | Tumor Necrosis Factor-alpha