6BGB:
reference: Controlling miRNA-like off-target effects of an siRNA with nucleobase modifications., Suter SR, Ball-Jones A, Mumbleau MM, Valenzuela R, Ibarra-Soza J, Owens H, Fisher AJ, Beal PA, Org Biomol Chem. 2017 Nov 22. doi: 10.1039/c7ob02654d. PMID: 29164215

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