NF-kB protein dimmers as nuclear transcription factor, they need to migrate to the nucleus, combined with DNA to have function. In most types of the normal cells under resting state, NF-KB was inactive and retain in the cytoplasm. They binding to a specific inhibitors called IK-B protein, which could bind to the Rel homology domain (RHD) of NF-kB and interfere with its nuclear localization sequence (NLS) function. These inhibitor proteins, which include IkBa, IkBb and IkBg, contain 6–7 ankyrin repeats that mediate binding to the RHD. These repeats are also present in the C-terminal halves of the NF-kB2/p100 and NF-kB1/p105 precursors, which also function as IkBs and retain their partners, the Rel proteins, in the cytoplasm. In order to activate the NF-kB molecular, the cells first need to separate the NF-kB protein from their inhibitors. There are two major signaling pathways lead to the IK-B protein inhibitor dissociation from NF-kB dimmer and let the translocation of NF-kB dimers from the cytoplasm into the nucleus.

Nuclear factor kappa-B (NF-κB) Pathway References