4NLJ:
reference: Structure of two crystal forms of sheep beta-lactoglobulin with EF-loop in closed conformation., Loch JI, Molenda M, Kopec M, Swiatek S, Lewinski K, Biopolymers. 2014 Aug;101(8):886-94. doi: 10.1002/bip.22471. PMID: 25098178

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