6XPN:
reference: Structural Features Mediating Zinc Binding and Transfer in the AztABCD Zinc Transporter System., Meni A, Yukl ET, Biomolecules. 2020 Aug 6;10(8). pii: biom10081156. doi: 10.3390/biom10081156. PMID: 32781785

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