Background：Nuclear factor k B(NF-kB) is a sequence-specific DNA-binding protein complex which regulates the expression of viral genomes, including the human immunodeficiency virus, and a variety of cellular genes, particularly those involved in immune and inflammatory responses. The members of the NF-Kb family in mammalian cells include the proto-oncogene c-Rel,p50/p105(NFkB1), p65(RelA), p52/p100(NFkB2), and RelB. All of these proteins share a conserved 300-amino acid region known as the Rel homology domain which is responsible for DNA binding, dimerization, and nuclear translocation of NF-Kb. The p65 subunit is a major component of NF-Kb complexes and is responsible for trans-activation. NF-kappa-B heterodimeric p65-p50 and p65-c-Rel complexes are transcriptional activators. The NF-kappa-B p65-p65 complex appears to be involved in invasin-mediated activation of IL-8 expression. The inhibitory effect of I-kappa-B upon NF-kappa-B the cytoplasm is exerted primarily through the interaction with p65. p65 shows a weak DNA-binding site which could contribute directly to DNA binding in the NF-kappa-B complex. It associates with chromatin at the NF-kappa-B promoter region via association with DDX1.
