The structure to the right is that of GCN 4.  It has an antiparallel interfacing between two helical ridges to form a dimer surface which has interdigitation of Leucine residues forming a "zipper." Looking at the structure, identify the following characteristics:

  • 33 residue Leucine Zipper -- there is a Leucine residue every 7 residues (heptad repeat), try to locate them.  How many heptad repeats are there in the 33 residue zipper?
  • What orientation is the structure? (right or left-handed?)
  • How are the portions of the dimer positioned in relation to each other, parallel or antiparallel?
  • How many Leucine residues of each helix are in the dimer region?