2FWS:
reference: Ca(2+) regulation in the na(+)/ca(2+) exchanger involves two markedly different ca(2+) sensors., Hilge M, Aelen J, Vuister GW, Mol Cell. 2006 Apr 7;22(1):15-25. PMID: 16600866

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