And once again, although both of these chains, alpha and beta, have the ability to bind ATP, only the beta has the ability to actually synthesize and release those ATP molecules into the matrix of the mitochondria and we'll discuss how that mechanism actually takes place in a future lecture. Now so we discussed the alpha and the beta units. Now let's move on to the gamma and the epsilon unit. So we have a single gamma and a single epsilon unit that actually organized. They combine to form something called essential stock. And this central stock is this elongated structure that runs through the inner cavity of that hexameric ring and it also connects to this structure that is found within the S not region as we'll see in just a moment.