4H5J:
reference: The Structure of Sec12 Implicates Potassium Ion Coordination in Sar1 Activation., McMahon C, Studer SM, Clendinen C, Dann GP, Jeffrey PD, Hughson FM, J Biol Chem. 2012 Oct 29. PMID: 23109340

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