1Q3M:
reference: The three-dimensional structure of bovine calcium ion-bound osteocalcin using 1H NMR spectroscopy., Dowd TL, Rosen JF, Li L, Gundberg CM, Biochemistry 2003 Jul 1;42(25):7769-79. PMID: 12820886

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