4KK3:
reference: Structural basis for recognizing phosphoarginine and evolving residue-specific protein phosphatases in gram-positive bacteria., Fuhrmann J, Mierzwa B, Trentini DB, Spiess S, Lehner A, Charpentier E, Clausen T, Cell Rep. 2013 Jun 27;3(6):1832-9. doi: 10.1016/j.celrep.2013.05.023. Epub 2013, Jun 13. PMID: 23770242

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