The lac repressor is a DNA-binding protein that regulates the expression of genes required for lactose metabolism in bacteria. In the absence of lactose, the repressor binds to the lac operon, preventing transcription and conserving cellular resources. When lactose is present, it is converted to allolactose, which binds the lac repressor and inhibits its ability to bind DNA. This release of repression allows transcription of genes necessary for lactose uptake and utilization.
