Claim: Sodium–hydrogen antiporter 3, a protein that in humans is encoded by the SLC9A3 gene found on the apical side of the epithelial cells of the proximal tubule of the nephron of the kidney, is primarily responsible for maintaining the balance of sodium.
Evidence: Sodium–hydrogen antiporter 3 also known as sodium–hydrogen exchanger 3 (NHE3) or solute carrier family 9 member 3 (SLC9A3) is a protein that in humans is encoded by the SLC9A3 gene. It is found on the apical side of the epithelial cells of the proximal tubule of the nephron of the kidney, in the apical membrane of enterocytes of the intestine, as well as the basolateral side of both duodenal and pancreatic cells responsible for the release of HCO−3 into the duodenal lumen. It is primarily responsible for maintaining the balance of sodium.