K-Cl co-transporter (IPR000076)

Short name: KCL_cotranspt

Family relationships


The K-Cl co-transporter (KCC) mediates the coupled movement of K+ and Cl- ions across the plasma membrane of many animal cells. This transport is involved in the regulatory volume decrease in response to cell swelling in red blood cells, and has been proposed to play a role in the vectorial movement of Cl- across kidney epithelia. The transport process involves one for one electroneutral movement of K+ together with Cl-, and, in all known mammalian cells, the net movement is outward [PMID: 8663127].

In neurones, it appears to play a unique role in maintaining low intracellular Cl-concentration, which is required for the functioning of Cl- dependent fast synaptic inhibition, mediated by certain neurotransmitters, such as gamma-aminobutyric acid (GABA) and glycine.

Two isoforms of the K-Cl co-transporter have been described, termed KCC1 and KCC2, containing 1085 and 1116 amino acids, respectively. They are both predicted to have 12 transmembrane (TM) regions in a central hydrophobic domain, together with hydrophilic N- and C-termini that are likely cytoplasmic. Comparison of their sequences with those of other ion-transporting membrane proteins reveals that they are part of a new superfamily of cation-chloride co-transporters, which includes the Na-Cl and Na-K-2Cl co-transporters. KCC1 is widely expressed in human tissues, while KCC2 is expressed only in brain neurones, making it likely that this is the isoform responsible for maintaining low Cl- concentration in neurones [PMID: 8663311, PMID: 9930699].

GO terms

Biological Process

GO:0006811 ion transport

Molecular Function

GO:0015379 potassium:chloride symporter activity

Cellular Component

GO:0016021 integral component of membrane

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.