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Basic leucine zipper (bZIP) domain of Activating Transcription Factor-3 (ATF-3) and similar proteins: a DNA-binding and dimerization domain ATF-3 is a Basic leucine zipper (bZIP) transcription factor that is induced by various stress signals such as cytokines, genetoxic agents, or physiological stresses. It is implicated in cancer and host defense against pathogens. It negatively regulates the transcription of pro-inflammatory cytokines and is critical in preventing acute inflammatory syndromes. Mice deficient with ATF3 display increased susceptibility to endotoxic shock induced death. ATF3 dimerizes with Jun and other ATF proteins; the heterodimers function either as activators or repressors depending on the promoter context. bZIP factors act in networks of homo and heterodimers in the regulation of a diverse set of cellular processes. The bZIP structural motif contains a basic region and a leucine zipper, composed of alpha helices with leucine residues 7 amino acids apart, which stabilize dimerization with a parallel leucine zipper domain. Dimerization of leucine zippers creates a pair of the adjacent basic regions that bind DNA and undergo conformational change. Dimerization occurs in a specific and predictable manner resulting in hundreds of dimers having unique effects on transcription.
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