||Bacteria Escherichia coli
||Benno Muller-hill, 1996, The Lac Operon: A Short History Of A Genetic Paradigm, Publisher: Walter de Gruyter. Berlin. New York. Part 3.2 pp.135
||Oehler S, Eismann ER, Krämer H, Müller-Hill B,The three operators of the lac operon cooperate in repression,EMBO J. 1990 Apr9(4):974, Fig. 2PubMed ID2182324
||We tested the effect of systematic destruction of all three lac operators of the chromosomal lac operon of Escherichia coli on repression by Lac repressor. Based on 5 percent lac operator in a free state, Lac repressor concentration=10 nM, Binding constant of Lac repressor to Lac operator=1E9 M
||Increase in repression=Decrease in constitutive expression. With all three operators, O1,O2,O3 expression of beta-galactosidase is repressed 1300 Fold. An 18 fold increase in repression was found in the presence of operator O1 only.