title: Protein quality control along the route to the plant vacuole.
abstract: To acquire information on the relationships between structural maturation of proteins in the endoplasmic reticulum (ER) and their transport along the secretory pathway, we have analyzed the destiny of an assembly-defective form of the trimeric vacuolar storage glycoprotein phaseolin. In leaves of transgenic tobacco, where assembly-competent phaseolin is correctly targeted to the vacuole, defective phaseolin remains located in the ER or a closely related compartment where it represents a major ligand of the chaperone BiP. Defective phaseolin maintained susceptibility to endoglycosidase H and was slowly degraded by a process that is not inhibited by heat shock or brefeldin A, indicating that degradation does not involve transport along the secretory pathway. These results provide evidence for the presence of a quality control mechanism in the ER of plant cells that avoids intracellular trafficking of severely defective proteins and eventually leads to their degradation.
authors.affiliation: Istituto Biosintesi Vegetali, Consiglio Nazionale delle Ricerche, Milan, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Pedrazzini
authors.forename: G
authors.initials: G
authors.lastname: Giovinazzo
authors.forename: A
authors.initials: A
authors.lastname: Bielli
authors.forename: M
authors.initials: M
authors.lastname: de Virgilio
authors.forename: L
authors.initials: L
authors.lastname: Frigerio
authors.forename: M
authors.initials: M
authors.lastname: Pesca
authors.forename: F
authors.initials: F
authors.lastname: Faoro
authors.forename: R
authors.initials: R
authors.lastname: Bollini
authors.forename: A
authors.initials: A
authors.lastname: Ceriotti
authors.forename: A
authors.initials: A
authors.lastname: Vitale
mesh_terms: D001692:Biological Transport; D002451:Cell Compartmentation; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D006868:Hydrolysis; D018832:Molecular Chaperones / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D011499:Protein Processing, Post-Translational; D014026:Nicotiana / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism*
chemical_list: D018832:Molecular Chaperones; D010940:Plant Proteins; C048826:phaseolin protein, Phaseolus vulgaris