Strawn R, Melichercik M, Green M, Stockner T, Carey J, Ettrich R. Symmetric allosteric mechanism of hexameric Escherichia coli arginine repressor exploits competition between L-arginine ligands and resident arginine residues. PLoS Comput Biol. 2010;6(6):e1000801. PMCID: PMC2880562