NKCC (Na-K-Cl协同转运蛋白)

NKCC (Na-K-Cl cotransporter) is a protein that aids in the active transport of sodium, potassium, and chloride into and out of cells. There are two varieties of this membrane transport protein, NKCC1 and NKCC2, however these are encoded by two different genes (SLC12A2 and SLC12A1 respectively) and are not isoforms. Two isoforms of the NKCC1/Slc12a2 gene result from keeping (isoform 1) or skipping (isoform 2) exon 21 in the final gene product. NKCC1 is widely distributed throughout the body; it has important functions in organs that secrete fluids. NKCC2 is found specifically in the kidney, where it serves to extract sodium, potassium, and chloride from the urine so that they can be reabsorbed into the blood. NKCC proteins are membrane transport proteins that transport sodium (Na), potassium (K), and chloride (Cl) ions across the cell membrane. Because they move each solute in the same direction, NKCC proteins are considered symporters.