It ultimately allows the hydrogen ions to flow from the intermembrane space and into the matrix down their electrochemical gradients. Now we also have this A subunit that is shown here and the A subunit basically lies on the outer portion of this C ring structure. And the A subune also plays a role in helping move those protons along the membrane, across the membrane, the inner membrane of the mitochondria. Now on top of that the A subunit actually also holds this. The asymmet also actually connects this C structure to this structure that is part of the F one unit. So as shown in the following diagram we have a single A sub unit that is attached onto this arm which consists of two B change and that in turn is attached onto that delta subunit.