4RDQ:
reference: Structure and insights into the function of a Ca(2+)-activated Cl(-) channel., Kane Dickson V, Pedi L, Long SB, Nature. 2014 Dec 11;516(7530):213-8. doi: 10.1038/nature13913. Epub 2014 Oct 22. PMID: 25337878

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