4TM6:
reference: An allosteric model for control of pore opening by substrate binding in the eutl microcompartment shell protein., Thompson MC, Cascio D, Leibly DJ, Yeates TO, Protein Sci. 2015 Mar 9. doi: 10.1002/pro.2672. PMID: 25752492

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