4TX5:
reference: The activator of apoptosis Smac-DIABLO acts as a tetramer in solution., Mastrangelo E, Vachette P, Cossu F, Malvezzi F, Bolognesi M, Milani M, Biophys J. 2015 Feb 3;108(3):714-23. doi: 10.1016/j.bpj.2014.11.3471. PMID: 25650938

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