So what happens is, because it's open to the outside, we have these hydrogen ions, protons which can enter this cavity. And when one of these enters the cavity, the positive charge basically interacts with a negative charge found on some type of side chain group of an amino acid. So for instance, it can interact with the CEO O negatively charged side chain group and it forms a bond. And so now we move on to this particular state. So this is bound and by binding it basically creates some type of change that increases the affinity of this pocket for lactose or some other type of sugar. So the lactose, which is a disaccharide by the way, moves into the pocket.