title: The rice RMR1 associates with a distinct prevacuolar compartment for the protein storage vacuole pathway.
abstract: Transport of vacuolar proteins from Golgi apparatus or trans-Golgi network (TGN) to vacuoles is a receptor-mediated process via an intermediate membrane-bound prevacuolar compartment (PVC) in plant cells. Both vacuolar sorting receptor (VSR) and receptor homology region-transmembrane domain-RING-H2 (RMR) proteins have been shown to function in transporting storage proteins to protein storage vacuole (PSV), but little is known about the nature of the PVC for the PSV pathway. Here, we use the rice RMR1 (OsRMR1) as a probe to study the PSV pathway in plants. Immunogold electron microscopy (EM) with specific OsRMR1 antibodies showed that OsRMR1 proteins were found in the Golgi apparatus, TGN, and a distinct organelle with characteristics of PVC in both rice culture cells and developing rice seeds, as well as the protein body type II (PBII) or PSV in developing rice seeds. This organelle, also found in both tobacco BY-2 and Arabidopsis suspension cultured cells, is morphologically distinct from the VSR-positive multivesicular lytic PVC or multivesicular body (MVB) and thus represent a PVC for the PSV pathway that we name storage PVC (sPVC). Further in vivo and in vitro interaction studies using truncated OsRMR1 proteins secreted into the culture media of transgenic BY-2 suspension cells demonstrated that OsRMR1 functions as a sorting receptor in transporting vicilin-like storage proteins.
authors.affiliation: School of Life Sciences, Centre for Cell and Developmental Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Shen
authors.forename: Junqi
authors.initials: J
authors.lastname: Wang
authors.forename: Yu
authors.initials: Y
authors.lastname: Ding
authors.forename: Sze Wan
authors.initials: SW
authors.lastname: Lo
authors.forename: Guillaume
authors.initials: G
authors.lastname: Gouzerh
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Neuhaus
authors.forename: Liwen
authors.initials: L
authors.lastname: Jiang
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D006056:Golgi Apparatus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D015388:Organelles / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012275:Oryza / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D016415:Sequence Alignment; D014617:Vacuoles / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D033921:Vesicular Transport Proteins