6CIU:
reference: "A threonine zipper that mediates protein-protein interactions: Structure and prediction"., Oi C, Treado JD, Levine ZA, Lim CS, Knecht KM, Xiong Y, O'Hern CS, Regan L, Protein Sci. 2018 Sep 10. doi: 10.1002/pro.3505. PMID: 30198622

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