1PTF:
reference: The 1.6 A structure of histidine-containing phosphotransfer protein HPr from Streptococcus faecalis., Jia Z, Vandonselaar M, Hengstenberg W, Quail JW, Delbaere LT, J Mol Biol 1994 Mar 11;236(5):1341-55. PMID: 8126724

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