Leucine zipper

•Leucine zipper is also known as leucine scissors.

•Leucine zipper motif is a DNA binding motif.

It is a molecule that is composed of 2 alpha helix.

These two alpha helix dimerizes to form a leucine zipper & this dimerization occurs at c terminal.

•There is leucine amino acid in c terminal which is hydrophobic amino acid.

The leucine zipper motif consist of a periodic repetition of a leucine residue at every 7 th position in c terminal end of the DNA binding domain.

•Leucine amino acid from 2 alpha helix interact and this interaction provide zipper like appearance.

•In N- terminal of this motif there are positively charge amino acid which will interact with negatively charged DNA.

Interaction of leucine zipper protein with dna occur at promoter enhancer or inverted repeats So leucine zipper is responsible for binding to the dna molecule

•Leucine zipper motif is found in many eukaryotic transcription factors.

Two types of zipper binding

1.DNA binding domain 2.   Dimerization domain

DNA binding domain

It occurs at N- terminal. It has a high concentration of basic amino acid i.e; lysine & Arginine. Lysine and arginine positively interact with the negatively charged phosphate of the DNA.

Dimerization domain

It occurs at c -terminal. Each monomer has an amphipathic (having both hydrophilic & hydrophobic parts)alpha helix with the hydrophobic surface interacting to create the dimer interface