The chloride potassium

symporter A symporter is an integral membrane protein that is involved in the transport of two (or more) different molecules across the cell membrane in the same direction. The symporter works in the plasma membrane and molecules are transported across the ...

is a

membrane transport protein A membrane transport protein (or simply transporter) is a membrane protein involved in the movement of ions, small molecules, and macromolecules, such as another protein, across a biological membrane. Transport proteins are integral transmembran ...

of the solute carrier family 12 that is present in the S3-segment of the renal

proximal tubule The proximal tubule is the segment of the nephron in kidneys which begins from the renal pole of the Bowman's capsule to the beginning of loop of Henle. It can be further classified into the proximal convoluted tubule (PCT) and the proximal straig ...

Page 780 and in the

neuron A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. N ...

. It functions in

renal chloride reabsorption Renal reabsorption of chloride ( Cl−) is a part of renal physiology, in order not to lose too much chloride in the urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ...

to transport

chloride The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the element chlorine (a halogen) gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride salts ...

across the

basolateral membrane Epithelial polarity is one example of the cell polarity that is a fundamental feature of many types of cells. Epithelial cells feature distinct 'apical', 'lateral' and 'basal' plasma membrane domains. Epithelial cells connect to one another via the ...

. Chloride potassium symporter can lower intracellular chloride concentrations below the

electrochemical equilibrium potential In a biological membrane, the reversal potential is the membrane potential at which the direction of ionic current reverses. At the reversal potential, there is no net flow of ions from one side of the membrane to the other. For channels that are ...

. The concentrations of K⁺ and Cl⁻ ions are high inside the cell due to the activities of Na⁺/K⁺ ATPase and NKCC cotransporter, respectively. Hence, their net driving force acting on the K/Cl cotransporter favours the exit of both K⁺ and Cl⁻ from the cell.

Types

Chloride potassium symporter are classified into: *

Chloride potassium symporter 4 Potassium-chloride transporter, member 4 is a chloride potassium symporter protein. It is encoded by the gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." ...

, predominating in the kidney. *

Chloride potassium symporter 5 Potassium-chloride transporter member 5 (aka: KCC2 and SLC12A5) is a neuron-specific chloride potassium symporter responsible for establishing the chloride ion gradient in neurons through the maintenance of low intracellular chloride concentration ...

, predominating in neurons. Each is encoded by a separate gene of the solute carrier family 12, hence accounting for the numbers succeeding its name. For example, chloride potassium symporter 5, or KCC2, is expressed through the SLC12A5 gene. Notably, symporters prior to 4 in the same family are other types of ion pumps. SLC12A3, for instance, is the

sodium-chloride symporter The sodium-chloride symporter (also known as Na+-Cl− cotransporter, NCC or NCCT, or as the thiazide-sensitive Na+-Cl− cotransporter or TSC) is a cotransporter in the kidney which has the function of reabsorbing sodium and chloride ions from t ...

References

* Transmembrane transporters Solute carrier family {{membrane-protein-stub