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Basic leucine zipper (bZIP) domain of Activating Transcription Factor-6 (ATF-6) and similar proteins: a DNA-binding and dimerization domain ATF-6 is a type I membrane-bound Basic leucine zipper (bZIP) transcription factor that binds to the consensus ER stress response element (ERSE) and enhances the transcription of genes encoding glucose-regulated proteins Grp78, Grp94, and calreticulum. ATF-6 is one of three sensors of the unfolded protein response (UPR) in metazoans; the others being the kinases Ire1 and PERK. It contains an ER-lumenal domain that detects unfolded proteins. In response to ER stress, ATF-6 translocates from the ER to the Golgi with simultaneous cleavage in a process called regulated intramembrane proteolysis (Rip) to its transcriptionally competent form, which enters the nucleus and upregulates target UPR genes. The three UPR sensor branches cross-communicate to form a signaling network. 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.",