2K2F:
reference: S100A1 and Calmodulin Compete for the Same Binding Site on Ryanodine Receptor., Wright NT, Prosser BL, Varney KM, Zimmer DB, Schneider MF, Weber DJ, J Biol Chem. 2008 Sep 26;283(39):26676-83. Epub 2008 Jul 23. PMID: 18650434

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