1BOC:
reference: The solution structures of mutant calbindin D9k's, as determined by NMR, show that the calcium-binding site can adopt different folds., Johansson C, Ullner M, Drakenberg T, Biochemistry 1993 Aug 24;32(33):8429-38. PMID: 8357794

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