You are studying bacteria and how a particular bacterium metabolizes maltose. Normally, the bacterium will only express a set of genes in the presence of maltose and absence of glucose. You identify a protein that affects transcription of these genes. You make a set of mutations and find that when you mutate the protein so that it is non-functional, the bacterium expresses the genes when glucose is low, regardless of the maltose level. What is the protein, and what is its function