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Translocation of Proteins into the Mitochondria

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,...

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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...

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Inositol-requiring kinase one or IRE1 is the most conserved eukaryotic unfolded protein response (UPR) receptor. It is a type I transmembrane protein kinase receptor with a distinctive site-specific RNase activity. As the binding mechanics of the misfolded proteins with the N-terminal domain of IRE-1 are unclear, three binding models — direct, indirect, and allosteric -- are proposed for receptor activation. Nevertheless, it is known that once a misfolded protein associates with IRE1, it...

Mitochondrial Protein Sorting

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Generally, polypeptides are unfolded by two distinct...

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Related Experiment Video

Updated: Jun 15, 2026

Subcellular Fractionation for ERK Activation Upon Mitochondrial-derived Peptide Treatment

Subcellular Fractionation for ERK Activation Upon Mitochondrial-derived Peptide Treatment

Published on: September 25, 2017

Peptides signal mitochondrial stress.

Janine Kirstein-Miles¹, Richard I Morimoto

¹Department of Biochemistry, Molecular Biology and Cell Biology, Rice Institute for Biomedical Research, Northwestern University, Evanston, IL 60208-3500, USA.

Cell Metabolism

|March 4, 2010

Summary

The mitochondrial unfolded protein response (UPR-mt) restores cellular balance by exporting damaged protein peptides from mitochondria. This retrograde signal triggers nuclear protective mechanisms against proteotoxic stress.

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Measurements of Physiological Stress Responses in C. Elegans

Measurements of Physiological Stress Responses in C. Elegans

Published on: May 21, 2020

Area of Science:

Molecular Biology
Cellular Stress Response
Mitochondrial Biology

Background:

Mitochondria maintain cellular function through protein homeostasis.
Proteotoxic stress disrupts mitochondrial function, necessitating adaptive responses.

Discussion:

The unfolded protein response in mitochondria (UPR-mt) acts as a retrograde signaling pathway.
This response involves the efflux of damaged protein-derived peptides from the mitochondrial matrix to the cytosol.
These peptides initiate nuclear-encoded protective measures.

Key Insights:

UPR-mt is a critical retrograde stress signal.
Peptide efflux from mitochondria is a key mechanism in UPR-mt.
UPR-mt links mitochondrial status to nuclear gene expression.

Outlook:

Further research into UPR-mt components could reveal therapeutic targets.
Understanding UPR-mt may offer insights into aging and neurodegenerative diseases.
Investigating the precise signaling cascade of UPR-mt is warranted.