1PRS:
reference: NMR-derived three-dimensional solution structure of protein S complexed with calcium., Bagby S, Harvey TS, Eagle SG, Inouye S, Ikura M, Structure 1994 Feb 15;2(2):107-22. PMID: 8081742

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