Death domain of the Nuclear Factor-KappaB1 precursor protein p105
Death Domain (DD) of the Nuclear Factor-KappaB1 (NF-kB1) precursor protein p105. The NF-kB family of transcription factors play a central role in cardiovascular growth, stress response, and inflammation by controlling the expression of a network of different genes. There are five NF-kB proteins, all containing an N-terminal REL Homology Domain (RHD). NF-kB1 (or p50) is produced from the processing of the precursor protein p105, which contains ANK repeats and a C-terminal DD in addition to the RHD. It is regulated by the classical (or canonical) NF-kB pathway. In the cytosol, p50 forms an inactive complex with RelA (or p65) and the Inhibitor of NF-kB (IkB). Activation is triggered by the phosphorylation and degradation of IkB, resulting in the active DNA-binding p50-RelA dimer to migrate to the nucleus. The classical pathway regulates the majority of genes activated by NF-kB including those encoding cytokines, chemokines, leukocyte adhesion molecules, and anti-apoptotic factors. In general, DDs are protein-protein interaction domains found in a variety of domain architectures. Their common feature is that they form homodimers by self-association or heterodimers by associating with other members of the DD superfamily including CARD (Caspase activation and recruitment domain), DED (Death Effector Domain), and PYRIN. They serve as adaptors in signaling pathways and can recruit other proteins into signaling complexes.