Entry into the Endoplasmic Reticulum: Protein Translocation, Folding and Quality Control

  • Sheara W. Fewell
  • Jeffrey L. Brodsky
Part of the Molecular Biology Intelligence Unit book series (MBIU)


Secretory proteins enter the ER after or concomitant with their synthesis on cytoplasmic ribosomes in a process known as translocation. In either case, nascent secretory proteins must be targeted to the translocation machinery at the ER membrane and must traverse the lipid bilayer of the ER through the translocation channel. Molecular chaperones in the cytosol and ER lumen assist translocation and facilitate protein folding and assembly in the lumen. Proteins that achieve their native conformation exit the ER and continue through the secretory pathway. Incompletely folded or unassembled proteins are recognized by a constitutively active quality control pathway in the ER that identifies aberrant proteins and targets them for destruction in the cytosol by the proteasome. This process is known as ER associated degradation (ERAD).


Endoplasmic Reticulum Cystic Fibrosis Transmembrane Conductance Regulator Endoplasmic Reticulum Membrane Protein Translocation Signal Recognition Particle 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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© Landes Bioscience and Springer Science+Business Media 2009

Authors and Affiliations

  1. 1.Department of Biological SciencesUniversity of PittsburghPittsburghUSA

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