title: Zinc transport and the inhibition of the L-type calcium channel are two separable functions of ZnT-1.
abstract: Traditionally, proteins are considered to perform a single role, be it as an enzyme, a channel, a transporter or as a structural scaffold. However, recent studies have described moonlighting proteins that perform distinct and independent functions; for example, TRPM7 is both an ion channel and a kinase. ZnT-1 is a member of the Carrier Diffusion Facilitator family that is expressed throughout the phylogenetic tree from bacteria to humans. Since its cloning in 1995, ZnT-1 is considered a major extruder of Zn2+based on its capability to protect cells against zinc toxicity. Recently, we reported that ZnT-1 inhibits the L-type calcium channel (LTCC), a major Zn2+and Ca2+entry pathway. Here we show that ZnT-1 is a dual-function protein by demonstrating that its abilities to exchange Zn2+/H+and to inhibit the LTCC are independent of each other and are mediated by different parts of the protein. Specifically, mutations in the membrane-spanning helices that render ZnT-1 unable to transport zinc do not prevent it from inhibiting the LTCC. Moreover, a fragment consisting of the intracellular ZnT-1 C-terminal, which lacks all ion-transfer segments, inhibits the LTCC as efficiently as wild-type ZnT-1. Our data therefore indicates that ZnT-1 performs two structurally independent functions related to zinc homeostasis.
authors.affiliation: Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel. Arie@bgu.ac.il Gitler@bgu.ac.il.
authors.forename: Eden
authors.initials: E
authors.lastname: Shusterman
authors.affiliation: Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel. Arie@bgu.ac.il Gitler@bgu.ac.il.
authors.forename: Ofer
authors.initials: O
authors.lastname: Beharier
authors.affiliation: Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel. Arie@bgu.ac.il Gitler@bgu.ac.il.
authors.forename: Shiri
authors.initials: S
authors.lastname: Levy
authors.affiliation: Department of Life Sciences, Faculty of Natural Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors.forename: Raz
authors.initials: R
authors.lastname: Zarivach
authors.affiliation: Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel. Arie@bgu.ac.il Gitler@bgu.ac.il.
authors.forename: Yoram
authors.initials: Y
authors.lastname: Etzion
authors.affiliation: Discipline of Physiology, The Bosch Institute, Faculty of Medicine, The University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Craig R
authors.initials: CR
authors.lastname: Campbell
authors.affiliation: Discipline of Physiology, The Bosch Institute, Faculty of Medicine, The University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Il-Ha
authors.initials: IH
authors.lastname: Lee
authors.affiliation: Discipline of Physiology, The Bosch Institute, Faculty of Medicine, The University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Anuwat
authors.initials: A
authors.lastname: Dinudom
authors.affiliation: Discipline of Physiology, The Bosch Institute, Faculty of Medicine, The University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: David I
authors.initials: DI
authors.lastname: Cook
authors.affiliation: Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Asher
authors.initials: A
authors.lastname: Peretz
authors.affiliation: Department of Cardiology, Barzilai University Medical Center, Ashkelon, Israel and Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors.forename: Amos
authors.initials: A
authors.lastname: Katz
authors.affiliation: Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel. Arie@bgu.ac.il Gitler@bgu.ac.il and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors.forename: Daniel
authors.initials: D
authors.lastname: Gitler
authors.affiliation: Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel. Arie@bgu.ac.il Gitler@bgu.ac.il and Discipline of Physiology, The Bosch Institute, Faculty of Medicine, The University of Sydney, Sydney, NSW 2006, Australia and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors.forename: Arie
authors.initials: A
authors.lastname: Moran
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D020746:Calcium Channels, L-Type / Q000737:chemistry* / Q000378:metabolism; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D057809:HEK293 Cells; D006706:Homeostasis; D006801:Humans; D017136:Ion Transport; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016415:Sequence Alignment; D014981:Xenopus / Q000502:physiology*; D015032:Zinc / Q000494:pharmacology*
chemical_list: D020746:Calcium Channels, L-Type; D027682:Cation Transport Proteins; D050505:Mutant Proteins; D015032:Zinc