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Related Concept Videos

Post-translational Translocation of Proteins to the RER01:27

Post-translational Translocation of Proteins to the RER

A sizable fraction of proteins destined for ER are first synthesized in the cell cytosol and then transported across the ER membrane–a process called post-translational translocation. Similar to cotranslationally translocated proteins, these proteins also use the Sec translocon complex to enter the ER lumen.
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 Translocation01:20

Cotranslational Protein Translocation

Translocation of proteins across membranes is an ancient process that occurs even in bacteria and archaebacteria. In fact, the components of the translocation machinery are still conserved between prokaryotes and eukaryotes.
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...
Protein Translocation Machinery on the ER Membrane01:28

Protein Translocation Machinery on the ER Membrane

The translocon complex situated on the ER membrane is the main gateway for the protein secretory pathway. It facilitates the transport of nascent peptides into the ER lumen and their insertion into 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.
Bacterial Translocation and Protein Secretion01:26

Bacterial Translocation and Protein Secretion

Bacterial protein secretion involves translocation systems to ensure proteins reach their designated locations, including the plasma membrane, periplasm, outer membrane, or the external environment. These translocation systems are vital for bacterial physiology, supporting processes like membrane assembly, enzymatic activity in the periplasm, and interactions with the external environment. The division of labor between Sec and Tat pathways ensures efficiency in handling proteins with diverse...
Overview of Secretory Vesicles01:33

Overview of Secretory Vesicles

Secretory vesicles, also known as dense core vesicles (DCVs), are membrane-bound vesicles that transport secretory proteins, such as hormones or neurotransmitters. Regulated secretory vesicles transport proteins from the trans-Golgi network to the exterior of the cell. Proteins present in regulated secretory vesicles are required to be rapidly exocytosed in large amounts upon a specific stimulus.
Various proteins regulate the aggregation of molecules inside the secretory vesicles. Chromogranins...
Overview of Protein Sorting and Transport01:45

Overview of Protein Sorting and Transport

Eukaryotic cells have different membrane-bound organelles with distinct protein requirements. The process by which proteins are targeted to a specific organelle is called protein sorting.
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...

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Related Experiment Video

Updated: Jun 15, 2026

In Situ Monitoring of Transiently Formed Molecular Chaperone Assemblies in Bacteria, Yeast, and Human Cells
08:58

In Situ Monitoring of Transiently Formed Molecular Chaperone Assemblies in Bacteria, Yeast, and Human Cells

Published on: September 2, 2019

SecB--a chaperone dedicated to protein translocation.

Philipp Bechtluft1, Nico Nouwen, Sander J Tans

  • 1Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and the Zernike Institute for Advanced Materials, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands. a.j.m.driessen@rug.nl.

Molecular Biosystems
|March 19, 2010
PubMed
Summary

SecB, a molecular chaperone in Gram-negative bacteria, prevents protein aggregation and unfolding. Single molecule studies show how SecB aids protein translocation across the cytoplasmic membrane.

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Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • SecB functions as a molecular chaperone in Gram-negative bacteria.
  • It is essential for post-translational protein translocation across the cytoplasmic membrane.

Purpose of the Study:

  • To investigate the role of SecB in protein translocation.
  • To understand how SecB affects protein folding pathways and prevents aggregation.

Main Methods:

  • Single molecule studies were employed.
  • Analysis of SecB's interaction with proteins during translocation.

Main Results:

  • The entire surface of SecB is utilized for its functions.
  • SecB influences protein folding pathways.
  • SecB prevents tertiary structure formation and aggregation.

Conclusions:

  • SecB plays a critical role in supporting protein translocation.
  • Its mechanism involves managing protein folding and preventing aggregation.