1BKS:
reference: Exchange of K+ or Cs+ for Na+ induces local and long-range changes in the three-dimensional structure of the tryptophan synthase alpha2beta2 complex., Rhee S, Parris KD, Ahmed SA, Miles EW, Davies DR, Biochemistry. 1996 Apr 2;35(13):4211-21. PMID: 8672457

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