Related Experiment Video
Updated: May 13, 2026

Visualization of Endoplasmic Reticulum Localized mRNAs in Mammalian Cells
Published on: December 17, 2012
Co-translational targeting and translocation of proteins to the endoplasmic reticulum
Yvonne Nyathi1, Barrie M Wilkinson, Martin R Pool
1Faculty of Life Sciences, University of Manchester, UK.
Abstract:
Co-translational protein targeting to the endoplasmic reticulum (ER), represents an evolutionary-conserved mechanism to target proteins into the secretory pathway. In this targeting pathway proteins possessing signal sequences are recognised at the ribosome by the signal recognition particle while they are still undergoing synthesis. This triggers their delivery to the ER protein translocation channel, where they are directly translocated into the ER. Here we review the current understanding of this translocation pathway and how molecular details obtained in the related bacterial system have provided insight into the mechanism of targeting and translocation. This article is part of a Special Issue entitled: Functional and structural diversity of endoplasmic reticulum.
Related Concept Videos
Post-translational Translocation of Proteins to the RER
Targeting proteins to the ER
Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...
Cotranslational Protein Translocation
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...
Directing Proteins to the Rough Endoplasmic Reticulum
Insertion of Single-pass Transmembrane Proteins in the RER
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
Protein Translocation Machinery on the ER Membrane
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Overview of Protein Sorting and Transport
Protein sorting can be of two types: signal-based sorting and vesicle-based trafficking. In signal-based sorting, specific amino acid sequences called sorting signals target proteins to the proper location inside the cell either via gated transport or by protein translocation. In gated transport, folded...

