5L8X:
reference: MtrA of the sodium ion pumping methyltransferase binds cobalamin in a unique mode., Wagner T, Ermler U, Shima S, Sci Rep. 2016 Jun 21;6:28226. doi: 10.1038/srep28226. PMID: 27324530

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