4XYP:
reference: Electrostatic Architecture of the Infectious Salmon Anemia Virus (ISAV) Core Fusion Protein Illustrates a Carboxyl-Carboxylate pH-Sensor., Cook JD, Soto-Montoya H, Korpela MK, Lee JE, J Biol Chem. 2015 Jun 16. pii: jbc.M115.644781. PMID: 26082488

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