2NUU:
reference: The crystal structure of the Escherichia coli AmtB-GlnK complex reveals how GlnK regulates the ammonia channel., Conroy MJ, Durand A, Lupo D, Li XD, Bullough PA, Winkler FK, Merrick M, Proc Natl Acad Sci U S A. 2007 Jan 23;104(4):1213-8. Epub 2007 Jan 12. PMID: 17220269

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