Na-K-2Cl symporter

solute carrier family 12 member 1
Identifiers
Symbol	SLC12A1
Alt. symbols	NKCC2
Entrez	6557
HUGO	10910
OMIM	600839
Orthologs	286
RefSeq	NM_000338
UniProt	Q13621
Other data
Locus	Chr. 15 q21.1

solute carrier family 12 member 2
Identifiers
Symbol	SLC12A2
Alt. symbols	NKCC1
Entrez	6558
HUGO	10911
OMIM	600840
Orthologs	20283
RefSeq	NM_001046
UniProt	P55011
Other data
Locus	Chr. 5 q23.3

The Na-K-Cl cotransporter (NKCC) is a protein that aids in the active transport of sodium, potassium, and chloride into and out of cells. In humans there are two isoforms of this membrane transport protein, NKCC1 and NKCC2, encoded by two different genes (SLC12A2 and SLC12A1 respectively). 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 human 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. They maintain electroneutrality by moving two positively charged solutes (sodium and potassium) alongside two parts of a negatively charged solute (chloride). Thus the stoichiometry of the NKCC proteins is 1Na:1K:2Cl.

NKCC1 is widely distributed throughout the body, especially in organs that secrete fluids, called exocrine glands. In cells of these organs, NKCC1 is commonly found in the basolateral membrane, the part of the cell membrane closest to the blood vessels. Its basolateral location gives NKCC1 the ability to transport sodium, potassium, and chloride from the blood into the cell. Other transporters assist in the movement of these solutes out of the cell through its apical surface. The end result is that solutes from the blood, particularly chloride, are secreted into the lumen of these exocrine glands, increasing the luminal concentration of solutes and causing water to be secreted by osmosis.

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Wikipedia