1SMT:
reference: Crystal structure of the cyanobacterial metallothionein repressor SmtB: a model for metalloregulatory proteins., Cook WJ, Kar SR, Taylor KB, Hall LM, J Mol Biol 1998 Jan 16;275(2):337-46. PMID: 9466913

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