2JYJ:
reference: RNA helical packing in solution: NMR structure of a 30 kDa GAAA tetraloop-receptor complex., Davis JH, Tonelli M, Scott LG, Jaeger L, Williamson JR, Butcher SE, J Mol Biol. 2005 Aug 12;351(2):371-82. PMID: 16002091

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