Leucine zipper
From Wikipedia, the free encyclopedia
Image:Coiledcoil-wheelcartoon.gif The leucine zipper is a type of structural motif found in parallel coiled coils. It is a common dimerization domain found in some DNA regulatory proteins.
[edit] Structure
The main feature of the leucine zipper domain is the predominance of leucine at the d position of the heptad repeat. Leucine zippers were first identified by sequence alignment of certain transcription factors which 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 LEU residue at every seventh position. Since there are 3.6 residues/turn in an alpha-helix, this positions one LEU at every second turn, just short of being exactly under each other in the coil.
The bZip family of transcription factors consist of a basic region which interacts with the backbone of a DNA molecule, and a leucine zipper region which is responsible for dimerization.
[edit] Biology
Leucine zipper regulatory proteins include fos and jun (the AP1 transcription factor), important regulators of normal development. If they are overproduced or mutated in a vital area, they may generate cancer. These proteins interact with the DNA as dimers (homo- or hetero-) and are also called basic zipper proteins (bZips).
[edit] References
- Landschulz WH, Johnson PF, McKnight SL. (1988) The leucine zipper: a hypothetical structure common to a new class of DNA-binding proteins. Science 240:1759-1764. PubMed abstractde:Leucin-Zipper
