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a transcription factor that regulates cytokine gene transcription. NF-κB is a target of glucocorticoid action.
NF-kappaBA pleiotropic transcription factor present in most cell types, which is involved in many biological processes such as inflammation, immunity, differentiation, cell growth, tumourigenesis and apoptosis. It forms a homo- or heterodimeric complex with Rel-like domain-containing proteins RELA/p65, RELB, NFKB1/p105, NFKB1/p50, REL and NFKB2/p52, binding the kappa-B sites in the DNA of their target genes. Individual dimers have distinct preferences for different kappa-B sites, binding with distinct affinity and specificity; different dimer combinations act as transcriptional activators or repressors.
NF-kappaB is controlled by various mechanisms of post-translational modification and subcellular compartmentalisation, as well as by interactions with other cofactors or co-repressors. NF-kappaB complexes are held in the cytoplasm in an inactive state, complexed with members of the NF-kappaB inhibitor (I-kappa-B) family. In conventional activation, I-kappa-B is phosphorylated by I-kappa-B kinases (IKKs) in response to different activators and subsequently degraded, liberating the active NF-kappaB complex, which translocates to the nucleus.