Now, on the basil lateral side, we have this Atpace pump. And what it does is it uses a single ATP to move three sodium ions against its electrochemical gradient towards the outside of the cell towards the interstitium. At the same time it moves to potassium into the cell. And what this protein pump does is it establishes an electrochemical gradient in which we have a higher concentration of sodium on the lumen side than inside our cell. Now, why is this important? Well, it's important because it allows the function of other proteins found within our cells, as we'll see in just a moment.