Basic leucine zipper (bZIP) domain of Plant Elongated/Long Hypocotyl5 (HY5)-like transcription factors and similar proteins: a DNA-binding and dimerization domain
This subfamily is predominantly composed of plant Basic leucine zipper (bZIP) transcription factors with similarity to Solanum lycopersicum and Arabidopsis thaliana HY5. Also included are the Dictyostelium discoideum bZIP transcription factors E and F. HY5 plays an important role in seedling development and is a positive regulator of photomorphogenesis. Plants with decreased levels of HY5 show defects in light responses including inhibited photomorphogenesis, loss of alkaloid organization, and reduced carotenoid accumulation. 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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