title: IDI7, a new iron-regulated ABC transporter from barley roots, localizes to the tonoplast.
abstract: A new Fe-deficiency-induced cDNA, IDI7, was isolated from the roots of Fe-deficient barley (Hordeum vulgare L. cv. Ehimehadaka no. 1). The transcript levels of IDI7 in roots strongly correlated with iron nutritional status, and induction by Fe-deficiency was restricted to roots. Excess treatment with heavy metal ions, such as copper, manganese, and zinc, did not cause obvious IDI7 induction in either leaves or roots. IDI7 encodes a 644 amino acid protein, and has features typical of ATP-binding cassette (ABC) transporters. Phylogenetic analysis revealed that IDI7 is closely related to the half-type ABC protein subfamily, which includes mammalian transporters associated with antigen processing (TAPs). A transiently expressed fusion protein of IDI7 to green fluorescent protein (GFP) was localized to tonoplasts in suspension-cultured tobacco (Nicotiana tabacum L.) cells. IDI7 and its orthologues are thought to comprise a new class of ABC transporters, located in the tonoplasts of higher plants. A possible Fe-deficiency adaptation role for IDI7 in barley root cells, involving transport across the tonoplast, is proposed.
authors.affiliation: Laboratory of Plant Molecular Physiology, Department of Applied Biological Chemistry, The University of Tokyo, 1-1 Yayoi, Bunkyo-ku, 113-8657 Tokyo, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Yamaguchi
authors.forename: Naoko-Kishi
authors.initials: NK
authors.lastname: Nishizawa
authors.forename: Hiromi
authors.initials: H
authors.lastname: Nakanishi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Mori
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D001483:Base Sequence; D001692:Biological Transport; D002478:Cells, Cultured; D003300:Copper / Q000494:pharmacology; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins; D001467:Hordeum / Q000187:drug effects / Q000235:genetics*; D007501:Iron / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008345:Manganese / Q000494:pharmacology; D008969:Molecular Sequence Data; D010802:Phylogeny; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D014026:Nicotiana / Q000166:cytology / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism; D015032:Zinc / Q000494:pharmacology
chemical_list: D018528:ATP-Binding Cassette Transporters; D018076:DNA, Complementary; D008164:Luminescent Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D008345:Manganese; D003300:Copper; D007501:Iron; D015032:Zinc