IκB Kinase ϵ Interacts with p52 and Promotes Transactivation via p65

The members of the NF-kappa B transcription factor family are key regulators of gene expression in the immune response. Different combinations of NF-kappa B subunits not only diverge in timing to induce transcription but also recognize varying sequences of the NF-kappa B-binding site of their target genes. The p52 subunit is generated as a result of processing of NF-kappa B2 p100. Here, we demonstrate that the non-canonical I kappa B kinase is an element of(IKK is an element of) directly interacts with p100. In a transactivation assay, IKK is an element of promoted the ability of p52 to transactivate gene expression. This effect was indirect, requiring p65, which was shown to be part of the IKK is an element of-p52 complex and to be phosphorylated by IKK is an element of. These novel interactions reveal a hitherto unknown function of IKK is an element of in the regulation of the alternative NF-kappa B activation pathway involving p52 and p65.