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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...
Structure of Porins01:21

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...
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...
Mitochondrial Membranes01:45

Mitochondrial Membranes

A single mitochondrion is a bean-shaped organelle enclosed by a double-membrane system. The outer membrane of mitochondria is smooth and contains many porins - the integral membrane transporters. Porins enable free diffusion of ions and small uncharged molecules through the outer mitochondrial membrane but limit the transport of molecules larger than 5000 Daltons. Further, the outer mitochondrial membrane forms a unique structure called membrane contact sites with other subcellular organelles,...

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Related Experiment Video

Updated: Jul 6, 2026

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

Proteomic view of mitochondrial function.

Kai Stefan Dimmer1, Doron Rapaport

  • 1Interfakultäres Institut für Biochemie, Hoppe-Seyler-Strasse, University of Tübingen, 72076 Tübingen, Germany.

Genome Biology
|March 12, 2008
PubMed
Summary
This summary is machine-generated.

Systematic studies have identified numerous mitochondrial proteins. A recent study reveals novel proteins that modify and regulate mitochondrial functions.

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Last Updated: Jul 6, 2026

Measurement of Protein Import Capacity of Skeletal Muscle Mitochondria
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Two-Step Tag-Free Isolation of Mitochondria for Improved Protein Discovery and Quantification

Published on: June 2, 2023

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Genetics

Background:

  • Mitochondria are crucial organelles involved in cellular respiration and energy production.
  • Previous genomic and proteomic studies have cataloged hundreds of mitochondrial proteins.
  • Understanding the functional roles of these proteins is essential for comprehending mitochondrial biology.

Purpose of the Study:

  • To identify novel proteins that act as modifiers and regulators of mitochondrial function.
  • To expand the understanding of the complex regulatory networks within mitochondria.

Main Methods:

  • Utilized advanced genomic and proteomic analysis techniques.
  • Integrated functional assays to validate the roles of newly identified proteins.

Main Results:

  • Identified a significant number of previously unknown mitochondrial proteins.
  • Demonstrated that these novel proteins play key roles in modulating mitochondrial activity and regulation.
  • These findings provide new insights into mitochondrial dynamics and cellular homeostasis.

Conclusions:

  • The study successfully identified novel mitochondrial modifiers and regulators.
  • These discoveries offer new avenues for research into mitochondrial diseases and therapeutic interventions.
  • This work significantly contributes to the field of mitochondrial biology.