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Basic leucine zipper (bZIP) domain of Cap'n'Collar (CNC) transcription factors: a DNA-binding and dimerization domain CNC proteins form a subfamily of Basic leucine zipper (bZIP) transcription factors that are defined by a conserved 43-amino acid region (called the CNC domain) located N-terminal to the bZIP DNA-binding domain. This subfamily includes Drosophila Cnc and four vertebrate counterparts, NFE2 (nuclear factor, erythroid-derived 2), NFE2-like 1 or NFE2-related factor 1 (NFE2L1 or Nrf1), NFE2L2 (or Nrf2), and NFE2L3 (or Nrf3). It also includes BACH1 and BACH2, which contain an additional BTB domain (Broad complex###Tramtrack###Bric-a-brac domain, also known as the POZ [poxvirus and zinc finger] domain). CNC proteins function during development and/or contribute in maintaining homeostasis during stress responses. In flies, Cnc functions both in development and in stress responses. In vertebrates, several CNC proteins encoded by distinct genes show varying functions and expression patterns. NFE2 is required for the proper development of platelets while the three Nrfs function in stress responses. Nrf2, the most extensively studied member of this subfamily, acts as a xenobiotic-activated receptor that regulates the adaptive response to oxidants and electrophiles. BACH1 forms heterodimers with small Mafs such as MafK to function as a repressor of heme oxygenase-1 (HO-1) gene (Hmox-1) enhancers. BACH2 is a B-cell specific transcription factor that plays a critical role in oxidative stress-mediated apoptosis. 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. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",