3RSB:
reference: Structure and Mutational Analysis of the Archaeal GTP:AdoCbi-P Guanylyltransferase (CobY) from Methanocaldococcus jannaschii: Insights into GTP Binding and Dimerization., Newmister SA, Otte MM, Escalante-Semerena JC, Rayment I, Biochemistry. 2011 May 4. PMID: 21542645

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