In genetics, an operator is a segment of DNA to which a transcription factor binds to regulate gene expression. The transcription factor is a repressor, which can bind to the operator to prevent transcription. The main operator (O2) in the classically defined lac operon is located slightly downstream of the promoter. Two additional operators, O1 and O3 are located at -82 and +412, respectively.

Read full article on Wikipedia · CC-BY-SA