And this CTP molecule is known as an allosteric inhibitor of this enzyme. And that's how we know that this enzyme is controlled allosterically inside our cells. So once again, these results suggest that the end product of the atcase initiative reaction must bind onto and inhibit the activity of that aspartate transcarbomolase. And this is known as negative feedback inhibition. Now, since the structure of the CTP, the citadine triphosphate, is nothing like the structure of these substrate molecules, that means this molecule does not bind to the active side, but it binds to some other regulatory site known as the allosteric site. And because it inhibits the activity of that enzyme, we call the CTP an allosteric inhibitor to this enzyme here.