title: Subcellular homeostasis of phytohormone auxin is mediated by the ER-localized PIN5 transporter.
abstract: The plant signalling molecule auxin provides positional information in a variety of developmental processes by means of its differential distribution (gradients) within plant tissues. Thus, cellular auxin levels often determine the developmental output of auxin signalling. Conceptually, transmembrane transport and metabolic processes regulate the steady-state levels of auxin in any given cell. In particular, PIN auxin-efflux-carrier-mediated, directional transport between cells is crucial for generating auxin gradients. Here we show that Arabidopsis thaliana PIN5, an atypical member of the PIN gene family, encodes a functional auxin transporter that is required for auxin-mediated development. PIN5 does not have a direct role in cell-to-cell transport but regulates intracellular auxin homeostasis and metabolism. PIN5 localizes, unlike other characterized plasma membrane PIN proteins, to endoplasmic reticulum (ER), presumably mediating auxin flow from the cytosol to the lumen of the ER. The ER localization of other PIN5-like transporters (including the moss PIN) indicates that the diversification of PIN protein functions in mediating auxin homeostasis at the ER, and cell-to-cell auxin transport at the plasma membrane, represent an ancient event during the evolution of land plants.
authors.affiliation: Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Genetics, Ghent University, 9052 Gent, Belgium.
authors.forename: Jozef
authors.initials: J
authors.lastname: Mravec
authors.forename: Petr
authors.initials: P
authors.lastname: Skůpa
authors.forename: Aurélien
authors.initials: A
authors.lastname: Bailly
authors.forename: Klára
authors.initials: K
authors.lastname: Hoyerová
authors.forename: Pavel
authors.initials: P
authors.lastname: Krecek
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Bielach
authors.forename: Jan
authors.initials: J
authors.lastname: Petrásek
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Vassilena
authors.initials: V
authors.lastname: Gaykova
authors.forename: York-Dieter
authors.initials: YD
authors.lastname: Stierhof
authors.forename: Petre I
authors.initials: PI
authors.lastname: Dobrev
authors.forename: Katerina
authors.initials: K
authors.lastname: Schwarzerová
authors.forename: Jakub
authors.initials: J
authors.lastname: Rolcík
authors.forename: Daniela
authors.initials: D
authors.lastname: Seifertová
authors.forename: Christian
authors.initials: C
authors.lastname: Luschnig
authors.forename: Eva
authors.initials: E
authors.lastname: Benková
authors.forename: Eva
authors.initials: E
authors.lastname: Zazímalová
authors.forename: Markus
authors.initials: M
authors.lastname: Geisler
authors.forename: Jirí
authors.initials: J
authors.lastname: Friml
mesh_terms: D017360:Arabidopsis / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D055786:Gene Knockout Techniques; D006706:Homeostasis / Q000502:physiology*; D007210:Indoleacetic Acids / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010641:Phenotype; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; C541719:PIN-FORMED 5 protein, Arabidopsis; D010937:Plant Growth Regulators