Related Experiment Video

Updated: Oct 9, 2025

Measurement of Protein Import Capacity of Skeletal Muscle Mitochondria
09:01

Measurement of Protein Import Capacity of Skeletal Muscle Mitochondria

Published on: January 7, 2022

2.8K

Protein Quality Control at the Mitochondrial Surface

Fabian den Brave1, Arushi Gupta1, Thomas Becker1

  • 1Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany.

Frontiers in Cell and Developmental Biology
|December 20, 2021
PubMed

Insights

Mitochondria use quality control to maintain outer membrane protein function, removing defective proteins via the ubiquitin-proteasome system. This ensures proper mitochondrial communication and biogenesis.

Area of Science:

  • Mitochondrial biology
  • Cellular quality control
  • Protein surveillance

Background:

  • The outer mitochondrial membrane (OMM) is crucial for cellular communication, metabolite transport, and signaling.
  • The translocase of the outer membrane (TOM complex) facilitates protein import into mitochondria.
  • Maintaining OMM protein functionality is vital for mitochondrial health and biogenesis.

Purpose of the Study:

  • To review the molecular mechanisms governing protein quality control at the OMM.
  • To highlight the importance of OMM protein surveillance for mitochondrial function.

Main Methods:

  • This review synthesizes current research on OMM protein quality control.
  • It examines the roles of degradation pathways and surveillance systems.

Main Results:

  • Quality control mechanisms remove defective and mistargeted OMM proteins.
  • The ubiquitin-proteasome system is key for OMM protein surveillance, unlike inner mitochondrial proteases.
  • Selective protein degradation regulates mitochondrial dynamics and mitophagy.

Conclusions:

  • Robust quality control of OMM proteins is essential for mitochondrial integrity and function.
  • Understanding these mechanisms provides insights into mitochondrial dynamics and disease.
  • The ubiquitin-proteasome system plays a central role in OMM protein surveillance.
Keywords:
Cdc48TOM complexmitochondriaprotein quality controlprotein sorting

More Related Videos

Author Spotlight: Two-Step Tag-Free Isolation of Mitochondria for Improved Protein Discovery and Quantification09:04

Author Spotlight: Two-Step Tag-Free Isolation of Mitochondria for Improved Protein Discovery and Quantification

Published on: June 2, 2023

6.8K
Assessment of Submitochondrial Protein Localization in Budding Yeast Saccharomyces cerevisiae08:55

Assessment of Submitochondrial Protein Localization in Budding Yeast Saccharomyces cerevisiae

Published on: July 19, 2021

3.1K

Related Concept Videos

Mitochondrial Protein Sorting01:39

Mitochondrial Protein Sorting

Mitochondria are double-membrane organelles of the eukaryotes involved in cellular metabolism, signaling, ATP synthesis, and programmed cell death.  Each of these processes requires specific proteins and enzymes that must be correctly sorted to the right mitochondrial subcompartment for the proper functioning of the organelle.
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
4.6K
Translocation of Proteins into the Mitochondria01:19

Translocation of Proteins into the Mitochondria

Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
7.6K
Porin Insertion in the Outer Mitochondrial Membrane01:12

Porin Insertion in the Outer Mitochondrial Membrane

Porins are beta-barrel proteins translocated to the mitochondrial outer membrane through the TOM complex into the intermembrane space. Porin precursors bind TIM chaperones within the intermembrane space and are guided to the Sorting and Assembly Machinery complex or SAM complex on the outer mitochondrial membrane.
Three models describe the assembly of porins by the SAM complex and their insertion into the outer membrane. Model 1 suggests that porins are assembled outside the SAM channel as the...
3.5K
Mitochondrial Precursor Proteins01:39

Mitochondrial Precursor Proteins

Mitochondrial precursors are partially unfolded or loosely folded polypeptide chains. Newly synthesized precursors are inhibited from spontaneously folding into their native conformation by the cytosolic chaperones, heat shock proteins 70 (Hsp70), and mitochondrial import stimulation factors (MSFs). Precursors bound to MSFs are guided to the TOM70-TOM37 receptors, while precursors bound to Hsp70  chaperones are targetted to TOM20-TOM22 receptor complexes.
Most of the mitochondrial...
2.7K
Protein Transport into the Inner Mitochondrial Membrane01:34

Protein Transport into the Inner Mitochondrial Membrane

Nuclear encoded mitochondrial precursors are imported to the inner membrane in a multistep process involving two separate translocons, TIM22 and TIM23. TIM23 is a cation-selective pore that remains closed by the N terminal segment of the protein. Negative charges on the TIM23 act as a receptor for the incoming precursor, pulling the positively charged matrix-targeting sequence for peptide insertion and translocation.
Transport of mitochondrial precursors across the TIM23 channel is driven by...
4.1K
The Inner Mitochondrial Membrane01:28

The Inner Mitochondrial Membrane

The inner mitochondrial membrane is the primary site of ATP synthesis. The inner membrane domain that forms a smooth layer adjacent to the outer membrane is called the inner boundary membrane. This domain contains membrane transporters that drive metabolites in and out of the mitochondria.  In contrast, the inner membrane network that invaginates into the matrix space is called the cristae membrane. This domain accounts for principle mitochondrial function as it accommodates the protein...
3.8K