1EY1:
reference: The structure of the transcriptional antiterminator NusB from Escherichia coli., Altieri AS, Mazzulla MJ, Horita DA, Coats RH, Wingfield PT, Das A, Court DL, Byrd RA, Nat Struct Biol 2000 Jun;7(6):470-4. PMID: 10881193

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