title: New and notable ion-channels in the sarcoplasmic/endoplasmic reticulum: do they support the process of intracellular Ca²⁺ release?
abstract: Intracellular Ca(2+) release through ryanodine receptor (RyR) and inositol trisphosphate receptor (IP3 R) channels is supported by a complex network of additional proteins that are located in or near the Ca(2+) release sites. In this review, we focus, not on RyR/IP3 R, but on other ion-channels that are known to be present in the sarcoplasmic/endoplasmic reticulum (ER/SR) membranes. We review their putative physiological roles and the evidence suggesting that they may support the process of intracellular Ca(2+) release, either indirectly by manipulating ionic fluxes across the ER/SR membrane or by directly interacting with a Ca(2+) -release channel. These channels rarely receive scientific attention because of the general lack of information regarding their biochemical and/or electrophysiological characteristics makes it difficult to predict their physiological roles and their impact on SR Ca(2+) fluxes. We discuss the possible role of SR K(+) channels and, in parallel, detail the known biochemical and biophysical properties of the trimeric intracellular cation (TRIC) proteins and their possible biological and pathophysiological roles in ER/SR Ca(2+) release. We summarise what is known regarding Cl(-) channels in the ER/SR and the non-selective cation channels or putative 'Ca(2+) leak channels', including mitsugumin23 (MG23), pannexins, presenilins and the transient receptor potential (TRP) channels that are distributed across ER/SR membranes but which have not yet been fully characterised functionally.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takeshima
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK.
authors.forename: Elisa
authors.initials: E
authors.lastname: Venturi
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Sitsapesan
mesh_terms: D000818:Animals; D020013:Calcium Signaling; D003226:Congresses as Topic; D006801:Humans; D007473:Ion Channels / Q000378:metabolism*; D007690:Polycystic Kidney Diseases / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*
chemical_list: D007473:Ion Channels