title: Potassium fluxes across the endoplasmic reticulum and their role in endoplasmic reticulum calcium homeostasis.
abstract: There are a number of known and suspected channels and exchangers in the endoplasmic reticulum that may participate in potassium flux across its membrane. They include trimeric intracellular cation channels permeable for potassium, ATP-sensitive potassium channels, calcium-activated potassium channels and the potassium-hydrogen exchanger. Apart from trimeric intracellular cation channels, which are specific to the endoplasmic reticulum, other potassium channels are also expressed in the plasma membrane and/or mitochondria, and their specific role in the endoplasmic reticulum has not yet been fully established. In addition to these potassium-selective channels, the ryanodine receptor and, potentially, the inositol 1,4,5-trisphosphate receptor are permeable to potassium ions. Also, the role of potassium fluxes across the endoplasmic reticulum membrane has remained elusive. It has been proposed that their main role is to balance the charge movement that occurs during calcium release and uptake from or to the endoplasmic reticulum. This review aims to summarize current knowledge on endoplasmic reticulum potassium channels and fluxes and their potential role in endoplasmic reticulum calcium uptake and release.
authors.affiliation: Department of Pharmacology, Centre of Excellence for Translational Medicine, University of Tartu, Ravila 19, Tartu, Estonia.
authors.forename: Malle
authors.initials: M
authors.lastname: Kuum
authors.affiliation: INSERM, U-769, Châtenay-Malabry F-92296, France; Univ Paris-Sud, Châtenay-Malabry F-92296, France.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Veksler
authors.affiliation: Department of Pharmacology, Centre of Excellence for Translational Medicine, University of Tartu, Ravila 19, Tartu, Estonia. Electronic address: allen.kaasik@ut.ee.
authors.forename: Allen
authors.initials: A
authors.lastname: Kaasik
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000737:chemistry / Q000378:metabolism; D027961:Potassium-Hydrogen Antiporters / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism
chemical_list: D053496:Inositol 1,4,5-Trisphosphate Receptors; D015221:Potassium Channels; D027961:Potassium-Hydrogen Antiporters; D019837:Ryanodine Receptor Calcium Release Channel; D011188:Potassium; D002118:Calcium
keywords: Calcium homeostasis; Endoplasmic reticulum; Intracellular potassium fluxes