title: Homomeric interaction of AtVSR1 is essential for its function as a vacuolar sorting receptor.
abstract: Vacuolar sorting receptors, BP80/VSRs, play a critical role in vacuolar trafficking of soluble proteins in plant cells. However, the mechanism of action of BP80 is not well understood. Here, we investigate the action mechanism of AtVSR1, a member of BP80 proteins in Arabidopsis (Arabidopsis thaliana), in vacuolar trafficking. AtVSR1 exists as multiple forms, including a high molecular mass homomeric complex in vivo. Both the transmembrane and carboxyl-terminal cytoplasmic domains of AtVSR1 are necessary for the homomeric interaction. The carboxyl-terminal cytoplasmic domain contains specific sequence information, whereas the transmembrane domain has a structural role in the homomeric interaction. In protoplasts, an AtVSR1 mutant, C2A, that contained alanine substitution of the region involved in the homomeric interaction, was defective in trafficking to the prevacuolar compartment and localized primarily to the trans-Golgi network. In addition, overexpression of C2A, but not wild-type AtVSR1, inhibited trafficking of soluble proteins to the vacuole and caused their secretion into the medium. Furthermore, C2A:hemagglutinin in transgenic plants interfered with the homomeric interaction of endogenous AtVSR1 and inhibited vacuolar trafficking of sporamin:green fluorescent protein. These data suggest that homomeric interaction of AtVSR1 is critical for its function as a vacuolar sorting receptor.
authors.affiliation: Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, Korea.
authors.forename: Hyeran
authors.initials: H
authors.lastname: Kim
authors.forename: Hyangju
authors.initials: H
authors.lastname: Kang
authors.forename: Mihue
authors.initials: M
authors.lastname: Jang
authors.forename: Jeong Ho
authors.initials: JH
authors.lastname: Chang
authors.forename: Yansong
authors.initials: Y
authors.lastname: Miao
authors.forename: Liwen
authors.initials: L
authors.lastname: Jiang
authors.forename: Inhwan
authors.initials: I
authors.lastname: Hwang
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism*; D002966:Clathrin / Q000378:metabolism; D022163:Clathrin-Coated Vesicles / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D050505:Mutant Proteins / Q000378:metabolism; D030821:Plants, Genetically Modified; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014617:Vacuoles / Q000378:metabolism*; D021601:trans-Golgi Network / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D002966:Clathrin; C106564:ELP protein, Arabidopsis; D050505:Mutant Proteins; D020033:Protein Isoforms; D011956:Receptors, Cell Surface; D049452:Green Fluorescent Proteins