| 4J4Q: reference: Opsin, a structural model for olfactory receptors?, Park JH, Morizumi T, Li Y, Hong JE, Pai EF, Hofmann KP, Choe HW, Ernst OP, Angew Chem Int Ed Engl. 2013 Oct 11;52(42):11021-4. doi: 10.1002/anie.201302374. , Epub 2013 Aug 26. PMID: 24038729 |
This OCA 
Structure page
uses Jmol,
developed by the Jmol Development Team
(documentation).