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Related Concept Videos

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,...
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...
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...
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 precursors...
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...
Mitochondria01:37

Mitochondria

Mitochondria are eukaryotic cellular organelles that are known to produce energy through a process called oxidative phosphorylation. Besides their primary function, mitochondria are involved in various cellular processes, including cell growth, differentiation, signaling, metabolism, and senescence. Age-related changes cause a decline in mitochondrial quality and integrity due to increased mitochondrial mutations and oxidative damage. Thus, aging can severely impact mitochondrial functions,...

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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

Protein quality control in mitochondria.

Takashi Tatsuta1

  • 1Institute for Genetics, University of Cologne, Cologne, Germany. T.Tatsuta@uni-koeln.de

Journal of Biochemistry
|August 12, 2009
PubMed
Summary
This summary is machine-generated.

Mitochondria maintain cell health through quality control. This review summarizes defense strategies, including chaperones and proteases, that prevent damaged protein buildup and counter mitochondrial stress.

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Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Mitochondria are vital for eukaryotic cell life and death.
  • Mitochondrial dysfunction is implicated in human aging (senescence) and neurodegenerative diseases.
  • Maintaining mitochondrial protein functionality is essential for cellular health.

Purpose of the Study:

  • To summarize current knowledge on mitochondrial defense strategies.
  • To highlight the role of quality-control mechanisms in maintaining mitochondrial integrity.
  • To discuss pathways that counteract mitochondrial stress.

Main Methods:

  • Literature review of mitochondrial quality control mechanisms.
  • Analysis of molecular chaperones and proteases involved in protein homeostasis.
  • Examination of signal transduction pathways responding to mitochondrial stress.

Main Results:

  • Mitochondria possess elaborate defense strategies to ensure protein quality.
  • Molecular chaperones and proteases form a network to monitor and clear damaged proteins.
  • Signal transduction pathways actively counteract mitochondrial stress.

Conclusions:

  • Robust quality-control systems are crucial for mitochondrial function and cellular survival.
  • Dysfunctional mitochondria contribute to aging and neurodegeneration.
  • Understanding these defense mechanisms offers insights into potential therapeutic targets.