3V5S:
reference: Structural insight into the ion-exchange mechanism of the sodium/calcium exchanger., Liao J, Li H, Zeng W, Sauer DB, Belmares R, Jiang Y, Science. 2012 Feb 10;335(6069):686-90. PMID: 22323814

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