Related Experiment Video

Updated: Feb 19, 2026

A Model Membrane Platform for Reconstituting Mitochondrial Membrane Dynamics
10:31

A Model Membrane Platform for Reconstituting Mitochondrial Membrane Dynamics

Published on: September 2, 2020

8.1K

Sequences flanking the transmembrane segments facilitate mitochondrial localization and membrane fusion by mitofusin

Xiaofang Huang1,2, Xin Zhou1,2, Xiaoyu Hu1,2

  • 1Department of Genetics and Cell Biology, College of Life Sciences, Nankai University, Tianjin 300071, China.

Proceedings of the National Academy of Sciences of the United States of America
|November 3, 2017
PubMed

Insights

Mitofusins (MFNs) mediate mitochondrial outer membrane fusion. Chimera studies reveal that MFN1 can function in endoplasmic reticulum (ER) fusion and that specific domains are critical for mitochondrial localization and membrane targeting.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Membrane Dynamics

Background:

  • Mitochondria undergo continuous fusion and fission, processes crucial for cellular function.
  • Outer mitochondrial membrane fusion relies on mitofusins (MFNs), a family of dynamin-like GTPases.
  • MFNs share structural similarities with atlastins (ATLs), which mediate endoplasmic reticulum (ER) fusion.

Purpose of the Study:

  • To elucidate the mechanistic basis of MFN-mediated membrane fusion.
  • To investigate the roles of specific MFN domains in mitochondrial fusion and localization.
  • To compare the functions of MFNs and ATLs in membrane fusion.

Main Methods:

  • Engineering of MFN-ATL chimeras by swapping protein domains.
  • Localization studies of MFN1 and its variants in ER and mitochondria.
  • Functional assays to assess membrane fusion and morphology maintenance.

Main Results:

  • MFN1, when localized to the ER via TM swapping with ATL1, supports ER fusion and morphology.
  • An amphipathic helix in the MFN1 C-terminal tail is exchangeable with ATL1's and essential for mitochondrial localization.
  • Hydrophobic residues amino-terminal to MFN1's TM segments influence membrane targeting but not fusion.

Conclusions:

  • Specific domains of MFNs dictate their localization and function in membrane fusion.
  • MFN and ATL GTPases share conserved and distinct mechanisms for membrane fusion.
  • This study provides key insights into the molecular mechanisms governing mitochondrial fusion.
Keywords:
endoplasmic reticulummembrane fusionmembrane targetingmitochondriamitofusin

More Related Videos

Assessment of Mitochondrial Fission/Fusion Dynamics in Kidney Proximal Tubular Cells06:14

Assessment of Mitochondrial Fission/Fusion Dynamics in Kidney Proximal Tubular Cells

Published on: November 14, 2025

606
Reconstitution of Msp1 Extraction Activity with Fully Purified Components05:52

Reconstitution of Msp1 Extraction Activity with Fully Purified Components

Published on: August 10, 2021

3.0K

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,...
13.5K
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...
5.0K
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...
5.8K
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...
3.8K
Energy to Drive Translocation01:37

Energy to Drive Translocation

Mitochondrial protein import is powered by two distinct energy sources: ATP hydrolysis and electrochemical potential across the inner membrane. Newly synthesized precursors are bound by cytosolic chaperones of the Hsp70 family, which guide them to the import receptors on the mitochondrial surface. Utilizing the energy of ATP hydrolysis, Hsp70 chaperones transfer these precursors to the TOM receptors on the mitochondrial outer membrane.
Generally, polypeptides are unfolded by two distinct...
2.9K
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,...
17.4K