2GCZ:
reference: Solution conformation of a neuronal nicotinic acetylcholine receptor antagonist alpha-conotoxin OmIA that discriminates alpha3 vs. alpha6 nAChR subtypes., Chi SW, Kim DH, Olivera BM, McIntosh JM, Han KH, Biochem Biophys Res Commun. 2006 Jun 23;345(1):248-54. Epub 2006 Apr 27. PMID: 16678128

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