3N5B:
reference: Crystal structure of the cyanobacterial signal transduction protein PII in complex with PipX., Zhao MX, Jiang YL, Xu BY, Chen Y, Zhang CC, Zhou CZ, J Mol Biol. 2010 Sep 24;402(3):552-9. Epub 2010 Aug 12. PMID: 20708625

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