title: AXR4 is required for localization of the auxin influx facilitator AUX1.
abstract: The AUX1 and PIN auxin influx and efflux facilitators are key regulators of root growth and development. For root gravitropism to occur, AUX1 and PIN2 must transport auxin via the lateral root cap to elongating epidermal cells. Genetic studies suggest that AXR4 functions in the same pathway as AUX1. Here we show that AXR4 is a previously unidentified accessory protein of the endoplasmic reticulum (ER) that regulates localization of AUX1 but not of PIN proteins. Loss of AXR4 resulted in abnormal accumulation of AUX1 in the ER of epidermal cells, indicating that the axr4 agravitropic phenotype is caused by defective AUX1 trafficking in the root epidermis.
authors.affiliation: Department of Biology, Indiana University, Bloomington, IN 47405, USA.
authors.forename: S
authors.initials: S
authors.lastname: Dharmasiri
authors.forename: R
authors.initials: R
authors.lastname: Swarup
authors.forename: K
authors.initials: K
authors.lastname: Mockaitis
authors.forename: N
authors.initials: N
authors.lastname: Dharmasiri
authors.forename: S K
authors.initials: SK
authors.lastname: Singh
authors.forename: M
authors.initials: M
authors.lastname: Kowalchyk
authors.forename: A
authors.initials: A
authors.lastname: Marchant
authors.forename: S
authors.initials: S
authors.lastname: Mills
authors.forename: G
authors.initials: G
authors.lastname: Sandberg
authors.forename: M J
authors.initials: MJ
authors.lastname: Bennett
authors.forename: M
authors.initials: M
authors.lastname: Estelle
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D001692:Biological Transport; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D018522:Gravitropism; D006540:Herbicides / Q000494:pharmacology; D007210:Indoleacetic Acids / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D019441:Plant Epidermis / Q000166:cytology / Q000378:metabolism; D018518:Plant Root Cap / Q000166:cytology / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism*; D030821:Plants, Genetically Modified; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism
chemical_list: C100794:AUX1 protein, Arabidopsis; C510828:AXR4 protein, Arabidopsis; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D006540:Herbicides; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; D011993:Recombinant Fusion Proteins; D015084:2,4-Dichlorophenoxyacetic Acid