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Related Concept Videos

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,...
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...
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 Folding Quality Check in the RER01:29

Protein Folding Quality Check in the RER

ER is the primary site for the maturation and folding of soluble and transmembrane secretory proteins. The calnexin cycle is a specific chaperone system that folds and assesses the confirmation of N-glycosylated proteins before they can exit the ER lumen. The primary players of this quality check pipeline are the lectins, ER-resident chaperones, and a glucosyl transferase enzyme. In case the calnexin system in the lumen fails to salvage a misfolded protein, it is transported to the cytoplasm...
The Proteasome01:13

The Proteasome

Eukaryotic cells can degrade proteins through several pathways. One of the most important among these is the ubiquitin-proteasome pathway. It helps the cell eliminate the misfolded, damaged, or unwarranted cytoplasmic proteins in a highly specific manner.
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. This involves participation of a series of enzymes including— E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 (ubiquitin...

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Visualization of Mitochondrial Respiratory Function using Cytochrome C Oxidase / Succinate Dehydrogenase (COX/SDH) Double-labeling Histochemistry
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Mitochondrial protein quality control: implications in ageing.

Bertrand Friguet1, Anne-Laure Bulteau, Isabelle Petropoulos

  • 1Laboratoire de Biologie et Biochimie Cellulaire du Vieillissement, EA 3106, Université Paris 7-Denis Diderot, Paris, France. bertrand.friguet@snv.jussieu.fr

Biotechnology Journal
|May 1, 2008
PubMed
Summary
This summary is machine-generated.

Mitochondria generate reactive oxygen species (ROS), leading to oxidized proteins linked with aging. Impaired mitochondrial protein maintenance, including Lon protease decline, contributes to age-related protein buildup and redox imbalance.

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Area of Science:

  • Mitochondrial biology
  • Cellular aging
  • Oxidative stress

Background:

  • Mitochondria are key sources of reactive oxygen species (ROS) and targets of oxidative damage.
  • Accumulation of oxidized proteins is linked to cellular aging.
  • Protein quality control, including repair and degradation, is vital for cellular health.

Purpose of the Study:

  • To investigate the role of mitochondrial protein maintenance in cellular aging.
  • To explore the function of methionine sulfoxide reductases and Lon protease in mitochondria.
  • To understand how age-related declines in these systems impact protein oxidation and redox homeostasis.

Main Methods:

  • Examined the enzymatic systems involved in mitochondrial protein repair (methionine sulfoxide reductases).
  • Investigated the function of the mitochondrial matrix proteolytic system, specifically the Lon protease.
  • Assessed age-related changes in the activity and expression of these mitochondrial maintenance systems.

Main Results:

  • Methionine sulfoxide reductases can reverse methionine oxidation in mitochondrial proteins.
  • The Lon protease plays a crucial role in degrading oxidized proteins within mitochondria.
  • Age-related declines in Lon protease activity/expression were observed, correlating with increased oxidized proteins.

Conclusions:

  • Impaired mitochondrial protein maintenance, particularly reduced Lon protease function, contributes to the accumulation of oxidized proteins during aging.
  • This impairment can disrupt mitochondrial redox homeostasis, exacerbating age-related cellular dysfunction.