2YN9:
reference: Cryo-EM structure of gastric H+,K+-ATPase with a single occupied cation-binding site., Abe K, Tani K, Friedrich T, Fujiyoshi Y, Proc Natl Acad Sci U S A. 2012 Nov 6;109(45):18401-6. doi:, 10.1073/pnas.1212294109. Epub 2012 Oct 22. PMID: 23091039

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