Synthesis of two lac repressor polypeptides in a mutant of Escherichia coli that has a new promoter for the lac operon mapping within the i gene

Consistent with the probable location of a mutant promoter for the lac operon within the i gene (Bruenn & DeLucia-Curtin, 1975), we have demonstrated that the mutant synthesizes a fragment of lac repressor, as well as a repressor monomer of normal size. The properties of these polypeptides argue that the mutation that gives rise to the new promoter is most likely only an alteration of a few base-pairs.