1GKA:
reference: The molecular basis of the coloration mechanism in lobster shell: beta-crustacyanin at 3.2-A resolution., Cianci M, Rizkallah PJ, Olczak A, Raftery J, Chayen NE, Zagalsky PF, Helliwell JR, Proc Natl Acad Sci U S A 2002 Jul 23;99(15):9795-800. PMID: 12119396

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