Protein Quality Control along the Route to the Plant Vacuole

• Published in: The Plant cell Vol. 9; no. 10; pp. 1869 - 1880
• Main Authors: Pedrazzini, Emanuela, Giovinazzo, Giovanna, Bielli, Anna, de Virgilio, Maddalena, Frigerio, Lorenzo, Pesca, Michela, Faoro, Franco, Bollini, Roberto, Ceriotti, Aldo, Vitale, Alessandro
• Format: Journal Article
• Language: English
• Published: England American Society of Plant Physiologists 01-10-1997
• Subjects: Antiserum; Biological Transport; Cell Compartmentation; Endoplasmic Reticulum - metabolism; Golgi Apparatus - metabolism; Hydrolysis; Molecular Chaperones - metabolism; Nicotiana - metabolism; Plant cells; Plant Proteins - chemistry; Plant Proteins - metabolism; Plants; Plants, Genetically Modified; Plants, Toxic; Polysaccharides; Protein Processing, Post-Translational; Protoplasts; Quality assurance; Secretory pathway; Storage proteins; Transgenic plants; Vacuoles; Vacuoles - metabolism
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.9.10.1869

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.