4FI3:
reference: Structure of AMP-PNP-bound vitamin B12 transporter BtuCD-F., Korkhov VM, Mireku SA, Locher KP, Nature. 2012 Oct 18;490(7420):367-72. doi: 10.1038/nature11442. Epub 2012 Sep 23. PMID: 23000901

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