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Updated: May 13, 2026
11:06
Multi-color Localization Microscopy of Single Membrane Proteins in Organelles of Live Mammalian Cells
Published on: June 30, 2018
Tom70 is essential for PINK1 import into mitochondria.
Hiroki Kato1, Qiping Lu, Doron Rapaport
1Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany. hmg1@tokyo-med.ac.jp
Plos One
|March 9, 2013
Summary
PTEN induced kinase 1 (PINK1) import into mitochondria is crucial for Parkinson's disease research. This study reveals PINK1 uses a unique import pathway dependent on Tom70, bypassing the core TOM complex.
Area of Science:
- Mitochondrial biology
- Neurodegenerative disease research
- Protein import mechanisms
Background:
- PTEN induced kinase 1 (PINK1) is a key gene linked to Parkinson's disease (PD).
- PINK1 is a serine/threonine kinase located in the outer mitochondrial membrane (OMM).
- The precise mechanism of PINK1 import into mitochondria is not fully understood.
Purpose of the Study:
- To elucidate the mechanism of PINK1 targeting and assembly into mitochondria.
- To investigate the role of the translocase of the outer mitochondrial membrane (TOM) complex in PINK1 import.
- To identify key proteins involved in the unique PINK1 mitochondrial import pathway.
Main Methods:
- Utilized a cell-free system to study PINK1 import.
- Investigated the necessity of Tom40, a core component of the TOM complex.
- Assessed the role of the import receptor Tom70 in PINK1 import.
- Examined the processing of PINK1's predicted mitochondrial targeting signal.
Main Results:
- PINK1 import into mitochondria occurs independently of Tom40, the main import channel component.
- The import receptor Tom70 is essential for PINK1 mitochondrial import.
- PINK1's predicted mitochondrial targeting signal is not processed by the mitochondrial processing peptidase.
- PINK1 import follows a distinct pathway not reliant on the core TOM complex.
Conclusions:
- PINK1 utilizes a unique mitochondrial import pathway.
- This pathway is independent of the TOM core complex but critically relies on the import receptor Tom70.
- Understanding this unique PINK1 import mechanism offers new insights into Parkinson's disease pathogenesis.
Related Concept Videos
01:39Mitochondrial 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...
Most of the mitochondrial precursors...
01:34Protein 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...
Transport of mitochondrial precursors across the TIM23 channel is driven by...
01:39Mitochondrial 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...
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
01:19Translocation 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,...
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,...
01:21Structure 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...
01:37Energy 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...
Generally, polypeptides are unfolded by two distinct...