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Related Concept Videos

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,...

Mitochondrial Protein Sorting

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 Membrane

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...

Structure of Porins

Structure of Porins

Mitochondria, chloroplasts, and gram-negative bacteria have transmembrane, beta-barrel proteins called porins to mediate the free diffusion of ions and metabolites across the membrane. Mitochondrial porin precursors contain conserved amino acid sequences called beta signals at their C-terminal. Beta signals have a motif of PoXGXXHyXHy (Po-Polar, X-Any amino acid, G-Glycine, Hy-LargeHydrophobic), which are crucial for precursor recognition to initiate precursor assembly. Beta-barrel precursors...

Mitochondrial Precursor Proteins

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 Membrane

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...

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Related Experiment Video

Updated: Jun 5, 2026

Mitochondrial Transformation in Baker's Yeast to Study Translation and Respiratory Complex Assembly

Mitochondrial Transformation in Baker's Yeast to Study Translation and Respiratory Complex Assembly

Published on: June 7, 2024

Inventory control: cytochrome c oxidase assembly regulates mitochondrial translation.

David U Mick¹, Thomas D Fox, Peter Rehling

¹Abteilung für Biochemie II, Universität Göttingen, D-37073 Göttingen, Germany.

Nature Reviews. Molecular Cell Biology

|December 24, 2010

Summary

Mitochondria synthesize some oxidative phosphorylation subunits. New research shows mitochondrial translation of cytochrome c oxidase subunit 1 (Cox1) is directly linked to the assembly of this essential respiratory complex.

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Mitochondrial Transformation in Baker's Yeast to Study Translation and Respiratory Complex Assembly

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Area of Science:

Mitochondrial biology
Cellular respiration
Protein biogenesis

Background:

Mitochondria possess their own genome and translation machinery.
Mitochondrial gene products are essential for oxidative phosphorylation.
Nuclear-encoded subunits must assemble with mitochondrially synthesized subunits.

Purpose of the Study:

To investigate the early assembly steps of cytochrome c oxidase.
To understand the relationship between mitochondrial translation and complex assembly.

Main Methods:

Analysis of mitochondrial translation processes.
Studying the assembly pathway of cytochrome c oxidase.

Main Results:

Mitochondrial translation of cytochrome c oxidase subunit 1 (Cox1) is a key early step.
Cox1 translation is directly coupled to the assembly of the cytochrome c oxidase complex.

Conclusions:

Mitochondrial translation is tightly regulated and integrated with complex assembly.
This coupling ensures efficient and accurate biogenesis of the oxidative phosphorylation system.