6MGI:
reference: Structural and biochemical evidence of the glucose 6-phosphate-allosteric site of maize C4-phosphoenolpyruvate carboxylase: its importance in the overall enzyme kinetics., Munoz-Clares RA, Gonzalez-Segura L, Juarez-Diaz JA, Mujica-Jimenez C, Biochem J. 2020 Jun 12;477(11):2095-2114. doi: 10.1042/BCJ20200304. PMID: 32459324

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