4MQX:
reference: Conformational changes required for H(+)/Cl(-) exchange mediated by a CLC transporter., Basilio D, Noack K, Picollo A, Accardi A, Nat Struct Mol Biol. 2014 May;21(5):456-63. doi: 10.1038/nsmb.2814. Epub 2014 Apr, 20. PMID: 24747941

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