4OKH:
reference: Crystal structure of calpain-3 penta-EF-hand (PEF) domain - a homodimerized PEF family member with calcium bound at the fifth EF-hand., Partha SK, Ravulapalli R, Allingham JS, Campbell RL, Davies PL, FEBS J. 2014 Jul;281(14):3138-49. doi: 10.1111/febs.12849. Epub 2014 Jun 9. PMID: 24846670

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