So we basically said that an allosteric protein or an allosteric enzyme will observe Cooperativity. And what that means is the binding of a molecule onto a side on that enzyme or protein will affect the affinity of the other sides for that same molecule. And again, we focused on this when we discuss hemoglobin. Now, the enzyme that we're going to focus on in the next several lectures that basically is controlled Alisterically is aspartate transcurbamylase. And we'll see exactly how this is done in the next several lectures. Now let's move on to the second regulation mechanism, reversible covalent modification.