title: I kappa B: a specific inhibitor of the NF-kappa B transcription factor.
abstract: In cells that do not express immunoglobulin kappa light chain genes, the kappa enhancer binding protein NF-kappa B is found in cytosolic fractions and exhibits DNA binding activity only in the presence of a dissociating agent such as sodium deoxycholate. The dependence on deoxycholate is shown to result from association of NF-kappa B with a 60- to 70-kilodalton inhibitory protein (I kappa B). The fractionated inhibitor can inactivate NF-kappa B from various sources--including the nuclei of phorbol ester-treated cells--in a specific, saturable, and reversible manner. The cytoplasmic localization of the complex of NF-kappa B and I kappa B was supported by enucleation experiments. An active phorbol ester must therefore, presumably by activation of protein kinase C, cause dissociation of a cytoplasmic complex of NF-kappa B and I kappa B by modifying I kappa B. this releases active NF-kappa B which can translocate into the nucleus to activate target enhancers. The data show the existence of a phorbol ester-responsive regulatory protein that acts by controlling the DNA binding activity and subcellular localization of a transcription factor.
mesh_terms: D001402:B-Lymphocytes / Q000502:physiology; D003593:Cytoplasm / Q000502:physiology; D004268:DNA-Binding Proteins / Q000502:physiology; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007145:Immunoglobulin kappa-Chains / Q000235:genetics*; D007700:Kinetics; D015394:Molecular Structure; D008970:Molecular Weight; D011485:Protein Binding; D012045:Regulatory Sequences, Nucleic Acid; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000037:antagonists & inhibitors* / Q000502:physiology
chemical_list: D004268:DNA-Binding Proteins; D007145:Immunoglobulin kappa-Chains; D014157:Transcription Factors; D013755:Tetradecanoylphorbol Acetate