N-terminal sub-domain of the Rel homology domain (RHD) of the reticuloendotheliosis viral oncogene homolog B (RelB) protein
Proteins containing the Rel homology domain (RHD) are metazoan transcription factors. The RHD is composed of two structural sub-domains; this model characterizes the N-terminal RHD sub-domain of the RelB family of transcription factors, categorized as class II NF-kappa B family members. In class II NF-kappa Bs, the RHD domain co-occurs with a C-terminal transactivation domain (TAD). NF-kappa B proteins are part of a protein complex that acts as a transcription factor, which is responsible for regulating a host of cellular responses to a variety of stimuli. This complex tightly regulates the expression of a large number of genes, and is involved in processes such as adaptive and innate immunity, stress response, inflammation, cell adhesion, proliferation and apoptosis. The cytosolic NF-kappa B complex is activated via phosphorylation of the ankyrin-repeat containing inhibitory protein I-kappa B, which dissociates from the complex and exposes the nuclear localization signal of the heterodimer (NF-kappa B and Rel). RelB, is unable to homodimerize but is a potent transactivator in a heterodimer with NF-kappa B1 (p50) or B2 (p52). It is involved in the regulation of genes that play roles in inflammatory processes and the immune response.