Now, in the process, protein complex one, three, and four all release protons. They pump protons from the mitochondrial matrix into the intermembrane space, thereby establishing the electrochemical gradient. Notice that protein complex number two is not a proton pump. And that means it does not actually pump any H ions into the intermembrane space. Now, the entire purpose of creating this electrochemical gradient is to basically create a high concentration of our H plus ions as well as a high amount of charge in the intermembrane space. And that allows these H plus ions to move down their electrochemical gradient from a region of high concentration to low concentration from a region of high charge to low charge through these channels in our ATP synthase.