3QXR:
reference: Crystal structure of a c-kit promoter quadruplex reveals the structural role of metal ions and water molecules in maintaining loop conformation., Wei D, Parkinson GN, Reszka AP, Neidle S, Nucleic Acids Res. 2012 Jan 28. PMID: 22287624

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