3PJS:
reference: Mechanism of activation gating in the full-length KcsA K+ channel., Uysal S, Cuello LG, Cortes DM, Koide S, Kossiakoff AA, Perozo E, Proc Natl Acad Sci U S A. 2011 Jul 5. PMID: 21730186

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