In leucine zipper model, Leucine residue seen after every

An a helix in which there is a periodic repeat of leucine residues at every seventh position. This occurs for eight helical turns and four leucine repeats. Similar structures have been found in a number of other proteins associated with the regulation of transcription in mammalian and yeast cells. (shown in the table below) It is thought that this structure allows two identical monomers or heterodimers (eg, Fos-Jun or Jun-Jun) to "zip together" in a coiled-coil and form a tight dimeric complex This protein-protein interaction may serve to enhance the association of the separate DNA binding domains with their target