IkappaB family members function by different mechanisms.
The IkappaB family of proteins regulates NF-kappaB-dependent transcription by inhibiting DNA binding and localizing these factors to the cell cytoplasm. IkappaBalpha does this by shifting the balance between nuclear import of Rel proteins and their export from the nucleus. Here we show that, unlike IkappaBalpha, IkappaBbeta and IkappaBepsilon appear to sequester p65 or c-Rel in the cytoplasm by inhibiting nuclear import. Furthermore, because IkappaBbeta does not undergo nucleocytoplasmic shuttling, it cannot remove nuclear proteins like IkappaBalpha does. We conclude that the mechanism of action differs among IkappaB family members.
Tam
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WF
Rosenstiel Basic Medical Sciences Research Center and the Department of Biology, Brandeis University, Waltham, Massachusetts 02454, USA.
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D021581:Active Transport, Cell Nucleus; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000502:physiology*; D049452:Green Fluorescent Proteins; D006801:Humans; D020672:I-kappa B Proteins; D008164:Luminescent Proteins / Q000235:genetics; D000072000:NF-KappaB Inhibitor alpha; D020569:Proto-Oncogene Proteins c-rel / Q000502:physiology
D004268:DNA-Binding Proteins; C083487:I kappa B beta protein; D020672:I-kappa B Proteins; D008164:Luminescent Proteins; C000606204:NFKBIA protein, human; D020569:Proto-Oncogene Proteins c-rel; D000072000:NF-KappaB Inhibitor alpha; D049452:Green Fluorescent Proteins