| 3R6U: reference: The Crystal Structure of the Substrate-Binding Protein OpuBC from Bacillus subtilis in Complex with Choline., Pittelkow M, Tschapek B, Smits SH, Schmitt L, Bremer E, J Mol Biol. 2011 Jun 1. PMID: 21658392 |
This OCA 
Structure page
uses Jmol,
developed by the Jmol Development Team
(documentation).