Sometimes called
bZIP motifs. A
dimer of two long
alpha helices which look like forceps pinching a piece of
DNA. These helices contain a large number of the
amino acid leucine, which forms an interdigitating
hydrophobic interface allowing the helices to stick. The leucines occur at regular intervals in the
sequence, seven residues apart. In many cases, the joining of the two components of the zipper are linked to DNA binding (
cooperativity), allowing these proteins to regulate DNA
transcription, such as the
Fos and
Jun proteins. These have a high degree of homology to
GCN4 which is a
yeast leucine zipper that also binds DNA.
schematic of a leucine zipper
| |
| |
\ /
\
( ) <- dimerization region, rich in leucine
\
/ \
/ \
|- D -|
|- N -| <- DNA binding region, rich in charged
|- A -| residues such as lysine and
arginine.