So now let's move on and discuss the F zero unit. Now the F one region basically contains the catalytic unit while the F zero region as we'll see in just a moment actually contains that structure that allows the movement of the protons, the hydrogen ions down their electrochemical gradient from the intermembrane side to the matrix side of our ATP synthase. So the F knot region is mostly hydrophobic and lies within the inner membrane of the mitochondria and basically consists of two types of units. We have the C unit, the C subunit as well as the A subunits. And together the C and the A subunit basically interact to form this proton channel that allows the movement of those protons across the membrane of the of the mitochondria, the inner membrane of the mitochondria. So the F knot region consists of ten to 14 C subunits.