title: Anion, cation, and zwitterion selectivity of phospholemman channel molecules.
abstract: Phospholemman (PLM), a 72-amino acid membrane protein with a single transmembrane domain, forms taurine-selective ion channels in lipid bilayers. Because taurine forms zwitterions, a taurine-selective channel might have binding sites for both anions and cations. Here we show that PLM channels indeed allow fluxes of both cations and anions, making instantaneous and voltage-dependent transitions among conformations with drastically different ion selectivity characteristics. This surprising and novel ion channel behavior offers a molecular explanation for selective taurine flux across cell membranes and may explain why molecules in the phospholemman family can induce cation- or anion-selective conductances when expressed in Xenopus oocytes.
authors.affiliation: Department of Internal Medicine (Cardiovascular Division), University of Virginia Health Sciences Center, Charlottesville 22908, USA.
authors.forename: G C
authors.initials: GC
authors.lastname: Kowdley
authors.forename: S J
authors.initials: SJ
authors.lastname: Ackerman
authors.forename: Z
authors.initials: Z
authors.lastname: Chen
authors.forename: G
authors.initials: G
authors.lastname: Szabo
authors.forename: L R
authors.initials: LR
authors.lastname: Jones
authors.forename: J R
authors.initials: JR
authors.lastname: Moorman
mesh_terms: D000818:Animals; D000838:Anions / Q000494:pharmacology; D002412:Cations / Q000494:pharmacology; D004285:Dogs; D004553:Electric Conductivity; D005260:Female; D007473:Ion Channels / Q000737:chemistry / Q000187:drug effects / Q000502:physiology*; D008051:Lipid Bilayers; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000737:chemistry* / Q000187:drug effects / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism; D009865:Oocytes / Q000187:drug effects / Q000502:physiology; D010750:Phosphoproteins / Q000737:chemistry* / Q000187:drug effects / Q000502:physiology*; D011189:Potassium Chloride / Q000494:pharmacology; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D012964:Sodium / Q000494:pharmacology; D013654:Taurine / Q000494:pharmacology*; D014982:Xenopus laevis
chemical_list: D000838:Anions; D002412:Cations; D007473:Ion Channels; D008051:Lipid Bilayers; D008565:Membrane Proteins; D010750:Phosphoproteins; D011994:Recombinant Proteins; C069141:phospholemman; D013654:Taurine; D011189:Potassium Chloride; D012964:Sodium