Related Experiment Video

Updated: Jan 14, 2026

Reconstitution of Msp1 Extraction Activity with Fully Purified Components
05:52

Reconstitution of Msp1 Extraction Activity with Fully Purified Components

Published on: August 10, 2021

2.9K

The C-Terminal Regions of TRAK Proteins Contain MIRO-Independent Mitochondrial Localization Domains

Lili Mitchell1, Kathryn E Reda1, Hijab Fatima1

  • 1Department of Biology, University of Richmond, Virginia, USA.

Cytoskeleton (Hoboken, N.J.)
|October 23, 2025
PubMed

Insights

TRAK proteins bind the mitochondrial outer membrane independently of MIRO, but require MIRO for mitochondrial localization. This suggests TRAK/MIRO interactions have roles beyond motor anchoring.

Area of Science:

  • Cell Biology
  • Mitochondrial Dynamics
  • Cytoskeletal Interactions

Background:

  • Current models propose MIRO GTPases anchor cytoskeletal motors to the mitochondrial outer membrane (MOM).
  • Previous work indicated weak interaction between MYO19 and MIRO, with a stronger MIRO-independent MOM-binding domain.
  • This study investigates if other MIRO interactors also possess MIRO-independent MOM binding.

Purpose of the Study:

  • To test if TRAK proteins exhibit MIRO-independent MOM binding.
  • To identify specific domains responsible for TRAK-MOM interactions.
  • To characterize the kinetics of TRAK-MIRO interactions.

Main Methods:

  • Quantitative fluorescence microscopy in MIRO1-2 double knockout mouse embryonic fibroblasts.
  • Analysis of GFP-TRAK truncations to identify localization domains.
  • Steady-state kinetic approaches, including fluorescence recovery after photobleaching (FRAP).

Main Results:

  • A MIRO-independent mitochondrial-binding domain was identified in the C-terminus of TRAK1 and TRAK2.
  • This domain showed a MOM localization pattern similar to full-length TRAK proteins.
  • TRAK MIRO-binding domains localized to mitochondria only when MIRO was expressed.
  • FRAP revealed faster exchange kinetics for TRAKMBD/MIRO interactions compared to full-length TRAK or the C-terminal domain alone.

Conclusions:

  • TRAK proteins possess a MIRO-independent domain for MOM binding.
  • TRAK localization to mitochondria is MIRO-dependent.
  • TRAK/MIRO interactions likely serve functions beyond simple anchoring of cytoskeletal motors.

More Related Videos

Multi-color Localization Microscopy of Single Membrane Proteins in Organelles of Live Mammalian Cells11:06

Multi-color Localization Microscopy of Single Membrane Proteins in Organelles of Live Mammalian Cells

Published on: June 30, 2018

9.0K
Experimental Approaches to Study Mitochondrial Localization and Function of a Nuclear Cell Cycle Kinase, Cdk113:15

Experimental Approaches to Study Mitochondrial Localization and Function of a Nuclear Cell Cycle Kinase, Cdk1

Published on: February 25, 2016

12.4K

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,...
12.1K
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...
4.8K
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...
5.6K
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...
3.5K
Cotranslational Protein Translocation01:20

Cotranslational Protein Translocation

Translocation of proteins across membranes is an ancient process that occurs even in bacteria and archaebacteria. In fact, the components of the translocation machinery are still conserved between prokaryotes and eukaryotes.
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...
9.6K
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...
2.7K