On the lumen side, this NaCl co transporter protein allows the movement of sodium down its electrochemical gradient from the lumen side to the inside of the cell. At the same time, it also moves the chloride along with the sodium. So we see that we have the reabsorption of chloride and sodium taking place, and we basically move these ions into the interstitial, the surrounding tissue of our distal convolute tubule. And these are eventually reabsorbed by the peritubular cavities found within and around our nephron. Now, the next type of protein channel that we have to consider is the calcium channel. So the calcium channel, just like this protein, is found on the apical side, on the side that points towards our lumen.