1X8W:
reference: Structure of the Tetrahymena ribozyme: base triple sandwich and metal ion at the active site., Guo F, Gooding AR, Cech TR, Mol Cell. 2004 Nov 5;16(3):351-62. PMID: 15525509

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