ⓘ Na-K-Cl cotransporter
The Na-K-Cl cotransporter is a protein that aids in the secondary active transport of sodium, potassium, and chloride into cells. In humans there are two isoforms of this membrane transport protein, NKCC1 and NKCC2, encoded by two different genes. Two isoforms of the NKCC1/Slc12a2 gene result from keeping or skipping exon 21 in the final gene product.
NKCC1 is widely distributed throughout the human body, it has important functions in organs that secrete fluids. NKCC2 is specifically in the kidney, where it serves to extract sodium, potassium and chloride in the urine, so that they can be reabsorbed into the blood.