3I9H:
reference: betagamma-Crystallin superfamily contains a universal motif for binding calcium., Aravind P, Mishra A, Suman SK, Jobby MK, Sankaranarayanan R, Sharma Y, Biochemistry. 2009 Nov 18. PMID: 19921810

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