Research progress of the structure and function of NF-κB and IκB in different animal groups.

The mammalian nuclear transcription factors NF-κB (Nuclear factor of kappa B) family plays a central role in the immune system, and participates in immune response, tumorigenesis and apoptosis by regulating the genes involved in the development and survival of lymphocytes. Inhibitor of kappa B (IκB) is an inhibitor of NF-κB, which keeps NF-κB in inactive state. When cells are stimulated by external signals, activated IκB is phosphated after a series of signal transmission, and then releases the NF-κB heterodimers that migrate into the nucleus and regulate gene expression. As an important functional protein, they exist in both higher animals and lower animals, and exhibit conserved functions. In this review, we summarize the investigation about NF-κB and IκB in several representative animals from invertebrates to vertebrates, in order to approach a more comprehensive and provide references for related researches.