They're the ones that catalyze the synthesis of the ATP and they're the ones that release that ATP molecules once a rotation actually takes place as we'll see in more detail in just a moment. In fact, notice that we have three different confirmations. That is, the beta subunits can actually exist in one of three different states and that's because we have three different reactions that have to be carried out by this alpha three, beta three hexamer. So we have the ten state or simply the T state. We have the Lose state or simply the L state and we have the open state or simply the O state. Now, in the open state in the open state once the ATP molecule is formed only when that beta submit is in the open state can the ATP molecule be released from that beta submune.