Now, what about the tripepptides and dipeptides? So, at the same time that this pump basically brings the sodium on the outside, this basically brings the sodium back inside. So for every three sodium we bring outside, there's a sodium on the apical side that is brought inside. And at the same time, this pumps our age to the outside of the cell. So this membrane protein is known as the sodium hydrogen exchange protein. So it exchanges one sodium for one hydrogen.