We actually have three individual alpha units and three individual beta units. And these three alpha and three beta units basically create this hexameric alpha three beta three ring structure as shown in the following diagram. So these alpha and beta units basically alternate to form this ring structure that consists of these six individual polypeptide chains. Now, the function of this hexameric structure, as we'll see in the future lecture, is to actually bind the ADP and the orthophosphate molecules to synthesize the ATP molecules and then release the ATP molecules into the matrix of the mitochondria. Now, although the alpha units can in fact bind the ATP molecules, only the beta units of this hexamer have the capability of actually synthesizing and releasing those ATP molecules. So once again, the three alpha and the three beta chains combine to form a hexameric alpha three beta three ring structure that will be responsible for catalyzing the synthesis of ATP molecules.