1RTP:
reference: Refined crystal structure of rat parvalbumin, a mammalian alpha-lineage parvalbumin, at 2.0 A resolution., McPhalen CA, Sielecki AR, Santarsiero BD, James MN, J Mol Biol 1994 Jan 14;235(2):718-32. PMID: 8289291

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