Existence and nature of the chloride pump.
Seven widely documented mechanisms of chloride transport across plasma membranes are: anion-coupled antiport, sodium symport, sodium-potassium-chloride symport, potassium chloride symport, proton-coupled symport, an electrochemical coupling process and chloride channels. No direct genetic evidence has yet been provided for primary active chloride transport despite numerous reports of cellular Cl(-)- stimulated ATPases coexisting, in the same tissue, with uphill chloride transport that could not be accounted for by the four common chloride transport processes. Cl(-)-stimulated ATPases are a common property of practically all biological cells with the major location being of mitochondrial origin. It also appears that plasma membranes are sites of Cl(-)-stimulated ATPase activity. Recent studies of Cl(-)-stimulated ATPase activity and chloride transport in the same membrane system, including liposomes, suggest a mediation by the ATPase in net movement of chloride up its electrochemical gradient across plasma membranes. Further studies, especially from a molecular biological perspective, are required to confirm a direct transport role to plasma membrane-localized Cl(-)-stimulated ATPases.
Gerencser
George A
GA
Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Box 100274, Gainesville, FL 32610-0274, USA. gag@phys.med.ufl.edu
Zhang
Jianliang
J
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D027321:Anion Transport Proteins / Q000235:genetics / Q000378:metabolism*; D001048:Aplysia; D001693:Biological Transport, Active; D002462:Cell Membrane / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D003001:Cloning, Molecular; D006801:Humans; D008564:Membrane Potentials; D010766:Phosphorylation
D027321:Anion Transport Proteins; D002712:Chlorides; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases