Function and activation of the transcription factor NF-kappa B in the response to toxins and pathogens.

The ubiquitous transcription factor NF-kappa B regulates the expression of a plethora of genes. In most cell types the dimeric DNA-binding form of the transcription factor is retained in the cytoplasm by physical association with the inhibitory I kappa B molecules. Five distinct DNA-binding subunits have so far been identified in vertebrates, which share a N-terminal homology region responsible for DNA-binding and dimerization. Exposure of cells to a variety of pathogenic and/or toxic agents leads to the generation of hydrogen peroxide and the inducible phosphorylation of I kappa B, which is a prerequisite for its proteolytic degradation. The DNA-binding subunits can subsequently enter the nucleus, bind to their cognate DNA and activate transcription.