Structure
The main feature of the leucine zipper domain is the predominance of the common amino acid leucine at the d position of the heptad repeat. Leucine zippers were first identified by sequence alignment of certain transcription factors that identified a common pattern of leucines every seven amino acids. These leucines were later shown to form the hydrophobic core of a coiled coil.
Each half of a leucine zipper consists of a short alpha-helix with a leucine residue at every seventh position. The standard 3.6-residues-per-turn alpha-helix structure changes slightly to become a 3.5-residues-per-turn alpha-helix. Known also as the heptad repeat, one leucine comes in direct contact with another leucine on the other strand every second turn.
The bZIP family of transcription factors consists of a basic region that interacts with the major groove of a DNA molecule through hydrogen bonding, and a hydrophobic leucine zipper region that is responsible for dimerization.
Read more about this topic: Leucine Zipper
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