2PA4:
reference: Active site geometry of glucose-1-phosphate uridylyltransferase., Thoden JB, Holden HM, Protein Sci. 2007 Jul;16(7):1379-88. Epub 2007 Jun 13. PMID: 17567737

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