title: ATP-binding cassette B4, an auxin-efflux transporter, stably associates with the plasma membrane and shows distinctive intracellular trafficking from that of PIN-FORMED proteins.
abstract: Intracellular trafficking of auxin transporters has been implicated in diverse developmental processes in plants. Although the dynamic trafficking pathways of PIN-FORMED auxin efflux proteins have been studied intensively, the trafficking of ATP-binding cassette protein subfamily B proteins (ABCBs; another group of auxin efflux carriers) still remains largely uncharacterized. In this study, we address the intracellular trafficking of ABCB4 in Arabidopsis (Arabidopsis thaliana) root epidermal cells. Pharmacological analysis showed that ABCB4 barely recycled between the plasma membrane and endosomes, although it slowly endocytosed via the lytic vacuolar pathway. Fluorescence recovery after photobleaching analysis revealed that ABCB4 is strongly retained in the plasma membrane, further supporting ABCB4's nonrecycling property. The endocytosis of ABCB4 was not dependent on the GNOM-LIKE1 function, and the sensitivity of ABCB4 to brefeldin A required guanine nucleotide exchange factors for adenosyl ribosylation factor other than GNOM. These characteristics of intracellular trafficking of ABCB4 are well contrasted with those of PIN-FORMED proteins, suggesting that ABCB4 may be a basic and constitutive auxin efflux transporter for cellular auxin homeostasis.
authors.affiliation: Department of Biological Sciences and Genomics and Breeding Institute, Seoul National University, Seoul, Korea.
authors.forename: Misuk
authors.initials: M
authors.lastname: Cho
authors.forename: Zee-Won
authors.initials: ZW
authors.lastname: Lee
authors.forename: Hyung-Taeg
authors.initials: HT
authors.lastname: Cho
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000235:genetics / Q000378:metabolism*; D000199:Actins / Q000037:antagonists & inhibitors / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D020126:Brefeldin A / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism*; D015638:Cytochalasin D / Q000494:pharmacology; D004705:Endocytosis; D036681:Fluorescence Recovery After Photobleaching; D017930:Genes, Reporter; D006056:Golgi Apparatus; D049452:Green Fluorescent Proteins / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D036701:Limonins / Q000494:pharmacology; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D019441:Plant Epidermis / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D055550:Protein Stability; D021381:Protein Transport; D019076:Transgenes; D014283:Triiodobenzoic Acids / Q000494:pharmacology
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D000199:Actins; D029681:Arabidopsis Proteins; D020126:Brefeldin A; D015638:Cytochalasin D; D049452:Green Fluorescent Proteins; D020662:Guanine Nucleotide Exchange Factors; D007210:Indoleacetic Acids; D036701:Limonins; D026901:Membrane Transport Proteins; D014283:Triiodobenzoic Acids; C522273:GNL1 protein, Arabidopsis; C088087:GNOM protein, Arabidopsis; C116363:PIN1 protein, Arabidopsis; C117013:AT5G57090 protein, Arabidopsis; C510494:Pgp4 protein, Arabidopsis; C105838:prieurianin; C052968:2,3,5-triiodobenzoic acid