3ZP8:
reference: Active-Site Monovalent Cations Revealed in a 1.55-A-Resolution Hammerhead Ribozyme Structure., Anderson M, Schultz EP, Martick M, Scott WG, J Mol Biol. 2013 May 25. pii: S0022-2836(13)00331-8. doi:, 10.1016/j.jmb.2013.05.017. PMID: 23711504

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