GO:0140570 extraction of mislocalized protein from mitochondrial outer membrane: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0140570 describes the removal of a mislocalized protein from the mitochondrial outer membrane, a protein quality-control process that prevents aggregation and organelle dysfunction.
• The conserved AAA-ATPase Msp1 (ATAD1 in humans) is the central extraction machine that recognizes and pulls mislocalized proteins out of the mitochondrial outer membrane [1,3].
• Msp1/ATAD1 extracts tail-anchored (TA) proteins that are mistargeted to mitochondria and, together with the GET pathway, transfers them to the endoplasmic reticulum for correct localization [2,6].
• Msp1 also cooperates with the proteasome to extract arrested mitochondrial import intermediates, linking extraction to degradation.
• Structural and reconstitution studies have defined the conserved elements that specialize ATAD1 as a membrane protein extraction machine [5,8].
• Dysregulation of Msp1/ATAD1 is linked to synaptic dysfunction and neurodegenerative processes, making this pathway a target for neurological research.
Description
The mitochondrial outer membrane (MOM) is a crowded, dynamic lipid bilayer that must maintain a precise protein composition for organelle function, signaling, and cell survival. Proteins that are mistargeted to the MOM can interfere with membrane integrity, aggregate, or disrupt mitochondrial dynamics, so cells have evolved dedicated quality-control systems to remove them. GO:0140570, extraction of mislocalized protein from mitochondrial outer membrane, captures the biological process that removes such aberrant proteins from the MOM. This process is essential for preserving mitochondrial proteostasis and for preventing the toxic consequences of protein mislocalization [1,3].
extraction of mislocalized protein from mitochondrial outer membrane At A Glance
| GO ID | GO:0140570 |
|---|---|
| GO term | extraction of mislocalized protein from mitochondrial outer membrane |
| Ontology | biological_process |
| Synonym | extraction of mislocalized protein from outer mitochondrion membrane |
| Major function | Removal of mislocalized proteins from the mitochondrial outer membrane to maintain mitochondrial proteostasis |
| Key machinery | The AAA-ATPase Msp1 in yeast and its ortholog ATAD1 in humans [1,3] |
| Cellular context | Mitochondrial outer membrane, with functional coupling to the endoplasmic reticulum and the proteasome [2,7] |
| Related pathway | GET pathway-mediated transfer of mislocalized tail-anchored proteins from mitochondria to the ER |
What Is GO:0140570?
GO:0140570 is defined as the removal of a mislocalized protein from the mitochondrial outer membrane. In practice, this means that a protein that has been incorrectly targeted to or inserted into the MOM is recognized, extracted from the lipid bilayer, and either redirected to its correct destination or delivered for degradation [1,2].
Why Is extraction of mislocalized protein from mitochondrial outer membrane Important in Cell Biology?
Extraction of mislocalized proteins from the mitochondrial outer membrane is a first line of defense against mitochondrial proteotoxic stress. Without this process, mistargeted proteins can accumulate at the MOM, impair mitochondrial import, disrupt membrane dynamics, and trigger cell death. The pathway is conserved from yeast to humans, and its central enzyme, Msp1/ATAD1, has been implicated in synaptic function and neurological disease, underscoring its broad importance for cell biology and medicine [1,3].
• Maintains mitochondrial proteostasis by removing aberrant proteins from the outer membrane.
• Prevents aggregation and toxicity of mislocalized tail-anchored proteins at mitochondria [2,6].
• Couples extraction to degradation by cooperating with the proteasome for arrested import intermediates.
• Enables rerouting of mislocalized proteins to the endoplasmic reticulum via the GET pathway.
• Supports mitochondrial import fidelity and organelle function [1,7].
• Is conserved from yeast Msp1 to human ATAD1, enabling cross-species mechanistic studies [3,5].
• Has structural features that specialize ATAD1 as a membrane protein extraction machine.
• Is linked to synaptic activities and neurological disease mechanisms.
• Provides a model for understanding general membrane protein quality control [1,8].
• Offers experimental tractability through reconstitution with purified components.
What Happens During extraction of mislocalized protein from mitochondrial outer membrane?
Recognition of mislocalized proteins at the mitochondrial outer membrane
In simple terms: The cell first has to spot a protein that is in the wrong place on the mitochondrial surface.
Mislocalized proteins that aberrantly insert into or associate with the mitochondrial outer membrane are recognized by the quality-control machinery. The AAA-ATPase Msp1/ATAD1 acts as a proofreading factor that identifies such substrates, including tail-anchored proteins that should not reside at mitochondria [1,2].
Extraction by the AAA-ATPase Msp1/ATAD1
In simple terms: A molecular machine grabs the misplaced protein and pulls it out of the membrane.
Msp1/ATAD1 uses ATP hydrolysis to extract mislocalized proteins from the mitochondrial outer membrane. This extraction activity is the defining event of GO:0140570 and has been reconstituted with fully purified components, demonstrating that Msp1 alone can perform the mechanical extraction step [1,8].
Transfer to the endoplasmic reticulum via the GET pathway
In simple terms: Some extracted proteins are not destroyed but are escorted to the endoplasmic reticulum where they belong.
For tail-anchored proteins that are mistargeted to mitochondria, the GET pathway mediates their transfer from mitochondria to the endoplasmic reticulum. This handoff allows the proteins to reach their correct destination rather than being degraded [2,6].
Cooperation with the proteasome for degradation
In simple terms: If a protein cannot be rescued, the extraction machine works with the proteasome to destroy it.
Msp1 cooperates with the proteasome to extract and degrade arrested mitochondrial import intermediates. This links the extraction process to protein degradation, ensuring that stalled or mislocalized proteins are cleared from the outer membrane.
Key Genes Involved in GO:0140570 extraction of mislocalized protein from mitochondrial outer membrane
The following genes and proteins are central to the extraction of mislocalized proteins from the mitochondrial outer membrane, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| MSP1 (yeast) | AAA-ATPase that extracts mislocalized proteins from the mitochondrial outer membrane | Primary model for mechanistic studies of GO:0140570 [1,8] |
| ATAD1 (human) | Human ortholog of Msp1; membrane protein extraction machine [3,5] | Linked to synaptic activities and neurological disease |
| GET3 | ATPase involved in GET pathway-mediated transfer of tail-anchored proteins | Mediates transfer of mislocalized TA proteins from mitochondria to ER |
| GET1 | GET pathway component that receives TA proteins at the ER | Required for rerouting of mislocalized TA proteins |
| GET2 | GET pathway component that receives TA proteins at the ER | Required for rerouting of mislocalized TA proteins |
| TOM70 | Mitochondrial import receptor for hydrophobic proteins | Involved in initial targeting of proteins to mitochondria |
| TOM20 | Mitochondrial import receptor for presequence-containing proteins | Context for mislocalization and quality control |
| TOM40 | Protein-conducting channel of the TOM complex | Site of import arrest that can trigger extraction |
| TIM23 | Inner membrane translocase component | Arrested import intermediates are substrates for Msp1 |
| TIM22 | Inner membrane translocase for carrier proteins | Related to mitochondrial protein sorting fidelity |
| ER-SURF components | ER surface factors that assist mitochondrial protein targeting | Couple ER and mitochondrial quality control |
| Proteasome subunits | Degrade extracted proteins | Cooperate with Msp1 for clearance of arrested intermediates |
| Ubiquitin ligases | May tag mislocalized proteins for degradation | Potential regulators of extraction-degradation coupling |
| Msp1 oligomer | Functional form of the extraction machine | Structural studies define extraction mechanism |
| ATAD1 mutants | Altered extraction activity | Used to dissect catalytic mechanism |
| TA proteins | Substrates that are mislocalized to mitochondria [2,6] | Model substrates for extraction and transfer studies [2,6] |
| Msp1-ATPase domain | Catalytic domain responsible for extraction | Reconstitution assays use purified ATPase |
How Is extraction of mislocalized protein from mitochondrial outer membrane Regulated?
The extraction of mislocalized proteins from the mitochondrial outer membrane is regulated by the availability of ATP, which drives the AAA-ATPase activity of Msp1/ATAD1 [1,8]. It is also functionally coupled to the GET pathway, which determines whether extracted tail-anchored proteins are transferred to the endoplasmic reticulum rather than degraded [2,6]. Cooperation with the proteasome provides a degradation route for arrested import intermediates, linking extraction to the ubiquitin-proteasome system. Structural elements within ATAD1 specialize its activity as a membrane protein extraction machine, and these features are conserved.
extraction of mislocalized protein from mitochondrial outer membrane and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ATAD1 | Neurological and synaptic dysfunction | ATAD1 knockout or point-mutation neurons |
| MSP1 | Mitochondrial protein quality control defects | MSP1 knockout yeast |
| GET3 | Mislocalization of tail-anchored proteins | GET3 knockout cells |
| GET1/GET2 | Impaired ER transfer of mislocalized proteins | GET1/GET2 knockout cells |
| Proteasome subunits | Defective degradation of arrested import intermediates | Proteasome inhibition or knockdown |
Neurological and synaptic dysfunction
Msp1/ATAD1 has been implicated in protein quality control and the regulation of synaptic activities. Dysfunction of ATAD1 may contribute to neurological disease mechanisms through impaired clearance of mislocalized proteins at mitochondria.
Mitochondrial proteostasis and neurodegeneration
Defects in extracting mislocalized proteins from the mitochondrial outer membrane can lead to accumulation of aberrant proteins, mitochondrial dysfunction, and cellular stress, processes relevant to neurodegenerative conditions [1,3].
Protein mislocalization in disease
Failure to remove mislocalized tail-anchored proteins from mitochondria and to transfer them to the endoplasmic reticulum via the GET pathway can disrupt organelle function and contribute to disease [2,6].
From extraction of mislocalized protein from mitochondrial outer membrane-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the effect of losing Msp1/ATAD1 extraction activity? | MSP1/ATAD1 knockout cell lines or yeast [1,3] |
| How does a specific ATAD1 mutation affect extraction? | Point-mutation knock-in of ATAD1 |
| Where does ATAD1 localize and act? | Tagged knock-in of ATAD1 with fluorescent tag |
| Can extraction be reconstituted in vitro? | Purified components with Msp1 and substrate |
| How does Msp1 cooperate with the proteasome? | Proteasome subunit knockout or inhibition |
| How are mislocalized TA proteins transferred to the ER? | GET pathway knockout or overexpression [2,6] |
How to Study the extraction of mislocalized protein from mitochondrial outer membrane Process
| Method | What It Measures | Typical Application |
|---|---|---|
| In vitro reconstitution | Direct extraction activity of purified Msp1 | Mechanistic studies of GO:0140570 |
| Proteomics | Accumulation of mislocalized proteins | Substrate identification |
| Fluorescence microscopy | Localization of tagged proteins | Visualizing extraction defects |
| Co-immunoprecipitation | Protein-protein interactions | Mapping cooperation with proteasome |
| Yeast genetics | Genetic interactions and growth phenotypes | Pathway dissection |
| ATPase assays | ATP hydrolysis by Msp1/ATAD1 | Measuring catalytic activity |
| Structural biology | Architecture of ATAD1 | Understanding extraction machine |
In vitro reconstitution of extraction
Reconstitution of Msp1 extraction activity with fully purified components allows direct measurement of the mechanical extraction step and is a powerful method to study GO:0140570.
Proteomics and substrate identification
Proteomic approaches can identify proteins that accumulate at the mitochondrial outer membrane when Msp1/ATAD1 is lost, revealing candidate substrates of the extraction pathway [1,7].
Imaging and localization studies
Fluorescence microscopy of tagged Msp1/ATAD1 and substrate proteins can visualize their localization and the consequences of extraction defects at mitochondria.
Genetic interaction and pathway analysis
Combining Msp1/ATAD1 mutants with GET pathway or proteasome mutants can define the genetic relationships that regulate extraction and downstream fate [2,6,7].
How CRISPR Can Be Used to Study GO:0140570 extraction of mislocalized protein from mitochondrial outer membrane
Knockout
CRISPR knockout of MSP1/ATAD1 or GET pathway genes can reveal the cellular consequences of losing extraction of mislocalized proteins from the mitochondrial outer membrane, including accumulation of aberrant proteins and mitochondrial dysfunction [1,2,3].
Point Mutation
Point mutations in ATAD1 can be introduced to dissect the catalytic and structural requirements for extraction, based on conserved elements identified in structural studies.
Knock-in
Knock-in of tagged ATAD1 or substrate proteins allows tracking of localization and dynamics in live cells, providing insight into where and when extraction occurs.
Overexpression
Overexpression of Msp1/ATAD1 or GET pathway components can test whether increased extraction capacity protects against mislocalized protein toxicity [2,6].
How EDITGENE Supports extraction of mislocalized protein from mitochondrial outer membrane Research
Researchers studying extraction of mislocalized protein from mitochondrial outer membrane-related genes often need to determine whether a candidate gene is causally involved in the pathway, how mutations affect extraction activity, and where the encoded protein acts within the cell. EDITGENE provides the CRISPR tools and services to build these models efficiently.
Contact EDITGENE today to design your custom CRISPR model for extraction of mislocalized protein from mitochondrial outer membrane research.
Frequently Asked Questions About extraction of mislocalized protein from mitochondrial outer membrane
What is GO:0140570?
GO:0140570 is the Gene Ontology biological process term for the extraction of mislocalized protein from mitochondrial outer membrane, the removal of aberrant proteins from the mitochondrial outer membrane.
What genes are involved in extraction of mislocalized protein from mitochondrial outer membrane?
Key genes include MSP1 in yeast and its human ortholog ATAD1, as well as GET pathway components such as GET3, GET1, and GET2, and proteasome subunits [1,2,7].
What is the role of Msp1 in mitochondrial protein quality control?
Msp1 is an AAA-ATPase that recognizes and extracts mislocalized proteins from the mitochondrial outer membrane, acting as a proofreading factor [1,3].
How does ATAD1 function as a membrane protein extraction machine?
ATAD1 uses ATP hydrolysis and conserved structural elements to pull mislocalized proteins out of the mitochondrial outer membrane.
What happens when mislocalized proteins are not extracted from mitochondria?
They can accumulate, impair mitochondrial function, and contribute to cellular stress and disease processes such as neurological dysfunction [1,3].
How is the GET pathway connected to mitochondrial protein extraction?
The GET pathway mediates the transfer of mislocalized tail-anchored proteins from mitochondria to the endoplasmic reticulum after extraction [2,6].
Does Msp1 cooperate with the proteasome?
Yes, Msp1 cooperates with the proteasome to extract and degrade arrested mitochondrial import intermediates.
Can extraction of mislocalized proteins be studied in vitro?
Yes, Msp1 extraction activity has been reconstituted with fully purified components, enabling direct mechanistic studies.
What diseases are linked to ATAD1 dysfunction?
ATAD1 has been implicated in protein quality control and regulation of synaptic activities, with relevance to neurological disease mechanisms.
What CRISPR models are useful for studying GO:0140570?
Knockout, point-mutation, knock-in, and overexpression models of MSP1/ATAD1 and GET pathway genes are useful for dissecting the pathway [1,2,5].
Conclusion
GO:0140570, extraction of mislocalized protein from mitochondrial outer membrane, is a conserved protein quality-control process that protects mitochondria from aberrant proteins. The AAA-ATPase Msp1/ATAD1 is the central extraction machine, working with the GET pathway and the proteasome to either reroute or degrade mislocalized proteins [1,2,7]. Understanding this process has implications for mitochondrial biology and neurological disease, and CRISPR-based models provide powerful tools to dissect its mechanism [3,5].
References
- 1. Matsumoto S et al.. 2023. Proofreading of protein localization mediated by a mitochondrial AAA-ATPase Msp1.. J Biochem 173(4):265-271 PMID: 36413760
- 2. Matsumoto S et al.. 2022. GET pathway mediates transfer of mislocalized tail-anchored proteins from mitochondria to the ER.. J Cell Biol 221(6) PMID: 35442388
- 3. Wang L et al.. 2020. Msp1/ATAD1 in Protein Quality Control and Regulation of Synaptic Activities.. Annu Rev Cell Dev Biol 36:141-164 PMID: 32886535
- 4. Koch C et al.. 2021. ER-SURF: Riding the Endoplasmic Reticulum Surface to Mitochondria.. Int J Mol Sci 22(17) PMID: 34502567
- 5. Wang L et al.. 2022. Conserved structural elements specialize ATAD1 as a membrane protein extraction machine.. Elife 11 PMID: 35550246
- 6. Dederer V et al.. 2019. Cooperation of mitochondrial and ER factors in quality control of tail-anchored proteins.. Elife 8 PMID: 31172943
- 7. Basch M et al.. 2020. Msp1 cooperates with the proteasome for extraction of arrested mitochondrial import intermediates.. Mol Biol Cell 31(8):753-767 PMID: 32049577
- 8. Fresenius HL et al.. 2021. Reconstitution of Msp1 Extraction Activity with Fully Purified Components.. J Vis Exp PMID: 34459824
