∞ generated and posted on 2016.02.07 ∞
Negative control of gene expression where transcription is blocked when excessive amounts of the products of metabolic pathways, encoded by the gene or genes in question, are present.
The idea behind corepresssion is that the repressor protein is active only when this product, serving as the corepressor, is present in high concentrations. That is, the default state is for the repressor to be not active, therefore not bound to the operator, and consequently not blocking transcription of the operon.
One typically finds corepression of operons that encode anabolic pathways, that is, where the pathway normally is expressed, with expression repressed only when the anabolic product catalytically generated by the pathway's gene products is present within the cell in sufficient densities.