InterPro domain: IPR004827

The basic-leucine zipper (bZIP) domain transcription factors [ 1 ] of eukaryotic are proteins that contain a basic region mediating sequence-specific DNA-binding followed by a leucine zipper region required for dimerisation.

Several structure of bZIP have been solved. The basic region and the leucine zipper form a contiguous alpha helice where the four hydrophobic residues of the leucine zipper are oriented on one side. This conformation allows dimerization in parallel and it bends the helices so that the newly functional dimer forms a flexible fork where the basic domains, at the N-terminal open end, can then interact with DNA. The two leucine zipper are therefore oriented perpendicular to the DNA [ 2 ].

1. Transcription factors 1: bZIP proteins. Cell 2, 101-68
2. The GCN4 basic region leucine zipper binds DNA as a dimer of uninterrupted alpha helices: crystal structure of the protein-DNA complex. null 71, 1223-37