1YSA:
reference: The GCN4 basic region leucine zipper binds DNA as a dimer of uninterrupted alpha helices: crystal structure of the protein-DNA complex., Ellenberger TE, Brandl CJ, Struhl K, Harrison SC, Cell 1992 Dec 24;71(7):1223-37. PMID: 1473154

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).