And it's the C ring, as we'll see in just a moment that actually rotates within the ATP synthase and that allows that gamma epsilon stalk to actually rotate and cause the binding change mechanism that we discussed in the previous lecture. So let's focus on the following diagram. So we have the inner membrane of the mitochondria. This is the matrix of the mitochondria and this is the intermembrane space. And this entire structure is the F knot region. And the F knot region lies within the membrane of the mitochondria within the inner membrane.