4GXY:
reference: Structural insights into ligand binding and gene expression control by an adenosylcobalamin riboswitch., Peselis A, Serganov A, Nat Struct Mol Biol. 2012 Nov;19(11):1182-4. doi: 10.1038/nsmb.2405. Epub 2012, Oct 14. PMID: 23064646

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