title: Phospholamban generates cation selective ion channels.
abstract: Phosholamban (PLN) is involved in the contractility of cardiac muscles by regulating the intracellular calcium concentration (Ca(2+)(cyt)) of cardiac myocytes. This occurs via a modulation of the sarco-/endoplasmic CaATPase (SERCA). In spite of high-resolution structures the molecular mode of PLN action is yet not known. In the present paper we readdress the question whether PLN proteins can generate ion channel activity. Reconstitution of PLN in planar lipid bilayers reveals single channel fluctuations, which are characterized by two conductance levels, long open/closed dwell times, moderate selectivity between monovalent cations and no perceivable Ca(2+) permeability. The PLN generated channel activity could be inhibited by a PLN antibody (abPLN) implying that the channel activity is indeed due to the inherent channel function of the PLN protein.
authors.affiliation: Dipartimento di Chimica, Università di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Firenze, Italy.
authors.forename: Serena
authors.initials: S
authors.lastname: Smeazzetto
authors.forename: Indra
authors.initials: I
authors.lastname: Schröder
authors.forename: Gerhard
authors.initials: G
authors.lastname: Thiel
authors.forename: Maria Rosa
authors.initials: MR
authors.lastname: Moncelli
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000276:immunology / Q000502:physiology*; D027682:Cation Transport Proteins / Q000502:physiology*; D002414:Cations, Monovalent / Q000378:metabolism; D002794:Choline / Q000378:metabolism; D055724:Electrophysiological Phenomena / Q000187:drug effects / Q000502:physiology; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D008051:Lipid Bilayers / Q000737:chemistry; D008564:Membrane Potentials / Q000502:physiology; D008567:Membranes, Artificial; D010713:Phosphatidylcholines / Q000737:chemistry; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D000099211:Phospholamban
chemical_list: D000911:Antibodies, Monoclonal; D002118:Calcium; D002135:Calcium-Binding Proteins; D027682:Cation Transport Proteins; D002414:Cations, Monovalent; D002794:Choline; D008051:Lipid Bilayers; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D011188:Potassium; D012964:Sodium; D000099211:Phospholamban