4XU4:
reference: PROTEIN STRUCTURE. Crystal structure of a mycobacterial Insig homolog provides insight into how these sensors monitor sterol levels., Ren R, Zhou X, He Y, Ke M, Wu J, Liu X, Yan C, Wu Y, Gong X, Lei X, Yan SF, Radhakrishnan A, Yan N, Science. 2015 Jul 10;349(6244):187-91. doi: 10.1126/science.aab1091. PMID: 26160948

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