4L9D:
reference: Calcium binding by the PKD1 domain regulates interdomain flexibility in Vibrio cholerae metalloprotease PrtV., Edwin A, Rompikuntal P, Bjorn E, Stier G, Wai SN, Sauer-Eriksson AE, FEBS Open Bio. 2013 Jun 27;3:263-70. doi: 10.1016/j.fob.2013.06.003. Print 2013. PMID: 23905008

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