GO:0180022 RQC-trigger complex: Components, Assembly and Research Methods, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0180022 (RQC-trigger complex, also called RQT or ASC-1 complex) is a ribosome disassembly machine that extracts stalled nascent polypeptides and splits collided ribosomes during ribosome-associated quality control.
• The complex contains a helicase module (yeast Rqt2 / human ASCC3), a ubiquitin-binding module (yeast Rqt3 / human ASCC2), and a ribosome-interacting module (yeast Rqt4 / human TRIP4), with human ASCC1 as an additional subunit.
• RQT/ASCC is recruited to 60S subunits carrying ubiquitinated nascent chains and uses ATP-dependent helicase activity to disassemble stalled ribosomal complexes.
• The human ASC-1 complex also acts as a transcriptional coactivator that interacts with transcription factors such as NF-kappa B.
• RQC-trigger complex dysfunction is linked to neurodegeneration, cancer, and ribosomopathies through failure to clear aberrant translation products.
• CRISPR knockout, point-mutation, knock-in, and overexpression models of ASCC3, ASCC2, ASCC1, and TRIP4 are essential for dissecting RQC-trigger complex biology.
Description
The RQC-trigger complex (GO:0180022) is a cellular component that functions as a ribosome disassembly machine within the ribosome-associated quality control (RQC) pathway. It is conserved from yeast to humans and is known as the RQT complex in yeast and the ASC-1 complex in mammals. The complex recognizes stalled ribosomes, extracts the nascent polypeptide, and splits the ribosomal subunits so that the aberrant translation product can be degraded and the ribosome recycled. Because translation stalls frequently on damaged mRNAs, rare codons, or polybasic stretches, the RQC-trigger complex is essential for proteostasis and cell survival. Researchers study GO:0180022 to understand how cells handle translation stress, how mutations in its subunits contribute to disease, and how its activity can be modulated for therapeutic benefit.
RQC-trigger complex At A Glance
| GO ID | GO:0180022 |
|---|---|
| GO term | RQC-trigger complex |
| Ontology | cellular_component |
| Synonym | activating signal cointegrator 1 complex; ASC-1 complex; RQT complex |
| Major function | ATP-dependent disassembly of stalled ribosomes and extraction of nascent polypeptides during ribosome-associated quality control |
| Subunits (yeast) | Rqt2 (helicase), Rqt3 (ubiquitin-binding), Rqt4 (ribosome-interacting) |
| Subunits (human) | ASCC3, ASCC2, ASCC1, TRIP4 |
| Pathway context | Ribosome-associated quality control (RQC) |
| Cellular localization | Cytosol, associated with 60S ribosomal subunits and collided ribosomes |
What Is GO:0180022?
According to the Gene Ontology, GO:0180022 (RQC-trigger complex) is a ribosome disassembly complex that dissociates stalled ribosome subunits as part of the ribosome quality control pathway. In yeast, the RQT complex is composed of the RNA helicase-family protein Rqt2 (human ASCC3), the ubiquitin-binding protein Rqt3 (human ASCC2), and Rqt4 (human TRIP4). The human complex has an additional component, ASCC1, and can act as a transcriptional coactivator by interacting with transcription factors such as NF-kappa B. Synonyms include activating signal cointegrator 1 complex, ASC-1 complex, and RQT complex.
Why Is RQC-trigger complex Important in Cell Biology?
The RQC-trigger complex is a central node in translation quality control, ensuring that stalled ribosomes are efficiently cleared to prevent the accumulation of toxic protein aggregates. Its dysfunction has been implicated in neurodegenerative diseases, cancer, and developmental disorders, making it a high-priority target for both basic and translational research.
• Prevents proteotoxic stress by clearing stalled translation complexes.
• Maintains ribosome homeostasis and recycling.
• Its helicase subunit ASCC3 is frequently mutated in cancer.
• ASCC1 mutations are linked to spinal muscular atrophy with congenital bone fractures.
• TRIP4 is a transcriptional coactivator involved in NF-kappa B signaling.
• RQC-trigger complex activity is required for neuronal survival under translation stress.
• Defects in RQC are associated with neurodegeneration.
• The complex is a potential target for antiviral and anticancer therapies.
• RQT/ASCC components are conserved from yeast to humans, enabling model organism studies.
• Its mechanism of action informs the design of ribosome-targeting drugs.
What Happens During RQC-trigger complex?
Recognition of stalled ribosomes
In simple terms: The complex first finds ribosomes that have stopped working.
Stalled ribosomes are recognized by the RQC-trigger complex through ubiquitination of ribosomal proteins and nascent chains. In yeast, Rqt3 binds to ubiquitinated 60S subunits, while in humans ASCC2 performs this function. This recognition step is a prerequisite for subsequent disassembly.
ATP-dependent ribosome splitting
In simple terms: The complex uses energy to break the ribosome apart.
The helicase subunit Rqt2 (ASCC3 in humans) hydrolyzes ATP to unwind rRNA and split the 60S and 40S subunits. This step releases the stalled nascent polypeptide for degradation.
Nascent chain extraction and degradation
In simple terms: The unfinished protein is pulled out and destroyed.
After splitting, the nascent polypeptide is extracted from the 60S subunit and targeted for proteasomal degradation. The RQC-trigger complex coordinates with other RQC factors such as Rqc2 and Ltn1 to ensure efficient clearance.
Transcriptional coactivation (human ASC-1 complex)
In simple terms: In humans, the complex also helps turn on genes.
The human ASC-1 complex, containing ASCC1, ASCC2, ASCC3, and TRIP4, can act as a transcriptional coactivator by interacting with transcription factors such as NF-kappa B. This dual role links translation quality control to gene expression regulation.
Key Genes Involved in GO:0180022 RQC-trigger complex
The following genes encode subunits and regulators of the RQC-trigger complex across species.
| Gene | Major Role | Research Relevance |
|---|---|---|
| ASCC3 | RNA helicase subunit; ATP-dependent ribosome splitting | Mutations in cancer; target for RQC studies |
| ASCC2 | Ubiquitin-binding subunit; recognizes ubiquitinated ribosomes | Essential for RQC substrate recruitment |
| ASCC1 | Human-specific subunit; links RQC to transcription | Mutations cause spinal muscular atrophy with congenital bone fractures |
| TRIP4 | Ribosome-interacting subunit; transcriptional coactivator | Involved in NF-kappa B signaling and development |
| Rqt2 | Yeast helicase ortholog of ASCC3 | Model for ribosome disassembly |
| Rqt3 | Yeast ubiquitin-binding ortholog of ASCC2 | Studied in ribosome collision recognition |
| Rqt4 | Yeast ortholog of TRIP4 | Required for RQT complex assembly |
| Rqc2 | RQC factor that extends nascent chains | Determines Rqc2-dependency of RQC |
| Ltn1 | E3 ubiquitin ligase for nascent chains | Targets stalled polypeptides for degradation |
| ZNF598 | E3 ubiquitin ligase that ubiquitinates collided ribosomes | Initiates RQC signaling |
| SDD1 | Endogenous RQC substrate in yeast | Used to study RQT complex function |
| HEL2 | Yeast helicase involved in RQC | Modulates RQT activity |
| NFKB1 | Transcription factor interacting with ASC-1 complex | Links RQC to inflammation |
| RELA | NF-kappa B subunit; interacts with ASC-1 | Transcriptional coactivation studies |
| DFRP1 | Ribosome-associated factor; knockout affects translation | Ribo-Seq studies |
| DFRP2 | Ribosome-associated factor; knockout affects translation | Ribo-Seq studies |
| GIR2 | Yeast protein involved in translation | Knockout models for RQC |
How Is RQC-trigger complex Regulated?
The RQC-trigger complex is regulated by ubiquitination of ribosomal proteins and nascent chains, which is mediated by E3 ligases such as ZNF598 and Ltn1. Polyubiquitin architecture on collided ribosomes maintains persistent RQC activity. Additionally, the human ASC-1 complex is regulated by interactions with transcription factors like NF-kappa B, linking its activity to cellular signaling.
RQC-trigger complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ASCC3 | Cancer, neurodegeneration | Knockout and point-mutation cell lines |
| ASCC1 | Spinal muscular atrophy with congenital bone fractures | Patient-derived iPSCs and knock-in mice |
| ASCC2 | Neurodevelopmental disorders | CRISPR knockout zebrafish |
| TRIP4 | Muscular dystrophy, cancer | Overexpression and knockout models |
| Rqt2 | Translation stress response | Yeast knockout strains |
Neurodegeneration
Defects in RQC-trigger complex components lead to accumulation of aberrant proteins, contributing to neurodegenerative diseases such as amyotrophic lateral sclerosis and Alzheimer's disease.
Cancer
ASCC3 mutations are found in various cancers, and loss of RQC function may promote tumorigenesis by allowing survival of cells with translation defects.
Ribosomopathies and developmental disorders
Mutations in ASCC1 cause spinal muscular atrophy with congenital bone fractures, a ribosomopathy-like disorder.
From RQC-trigger complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does ASCC3 helicase activity drive ribosome splitting? | Point mutation of ATPase domain |
| How does ASCC1 mutation affect RQC? | Knock-in of patient mutations |
| What is the interactome of RQC-trigger complex? | Tagged knock-in for proteomics |
| Can overexpression rescue RQC defects? | Overexpression of ASCC3 in knockout cells |
| What genes are essential for RQC? | CRISPR library screening |
| How does RQC-trigger complex affect translation? | Ribo-Seq in knockout cells |
How to Study the RQC-trigger complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Ribo-Seq | Ribosome footprint density | Detect stalled ribosomes |
| RNA-Seq | Transcript abundance | Gene expression changes |
| Proteomics | Protein interactions and modifications | Identify complex components |
| Western blot | Protein levels and ubiquitination | Validate knockout/overexpression |
| Immunofluorescence | Subcellular localization | Study complex assembly |
| CRISPR screening | Gene essentiality | Discover RQC regulators |
| Polysome profiling | Ribosome subunit distribution | Assess disassembly defects |
Ribo-Seq
Ribo-Seq measures ribosome occupancy and reveals stalled ribosomes, providing a global view of RQC-trigger complex activity.
RNA-Seq
RNA-Seq quantifies changes in gene expression upon RQC-trigger complex perturbation, linking translation to transcription.
Proteomics
Affinity purification coupled to mass spectrometry identifies interactors and post-translational modifications of the complex.
Imaging
Fluorescence microscopy visualizes co-localization of RQC-trigger complex subunits with ribosomal markers and stress granules.
How CRISPR Can Be Used to Study GO:0180022 RQC-trigger complex
Knockout
CRISPR knockout of ASCC3, ASCC2, ASCC1, or TRIP4 in cell lines abolishes RQC-trigger complex function, leading to accumulation of stalled ribosomes and nascent chains.
Point Mutation
Point mutations in the helicase domain of ASCC3 (e.g., ATPase-dead mutants) dissect the requirement for ATP hydrolysis in ribosome splitting.
Knock-in
Knock-in of epitope tags or patient-derived mutations allows tracking of endogenous complex subunits and modeling of disease-associated variants.
Overexpression
Overexpression of wild-type or mutant ASCC3, ASCC2, ASCC1, or TRIP4 tests gain-of-function effects and rescue of knockout phenotypes.
How EDITGENE Supports RQC-trigger complex Research
Researchers studying RQC-trigger complex-related genes often need to determine whether a candidate gene is causally involved in translation quality control, disease progression, or transcriptional regulation. EDITGENE provides comprehensive CRISPR services to generate precisely engineered cell models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for RQC-trigger complex research.
Frequently Asked Questions About RQC-trigger complex
What is the RQC-trigger complex?
The RQC-trigger complex (GO:0180022) is a ribosome disassembly machine that splits stalled ribosomes and extracts nascent polypeptides during ribosome-associated quality control.
What genes are involved in the RQC-trigger complex?
Key genes include ASCC3, ASCC2, ASCC1, and TRIP4 in humans, and Rqt2, Rqt3, and Rqt4 in yeast.
What is the function of ASCC3?
ASCC3 is an RNA helicase that uses ATP to split stalled ribosomes and extract nascent chains.
How is the RQC-trigger complex regulated?
It is regulated by ubiquitination of ribosomal proteins and nascent chains, mediated by E3 ligases such as ZNF598 and Ltn1.
What diseases are associated with RQC-trigger complex mutations?
Mutations in ASCC1 cause spinal muscular atrophy with congenital bone fractures, and ASCC3 mutations are linked to cancer and neurodegeneration.
What is the ASC-1 complex?
The ASC-1 complex is the human form of the RQC-trigger complex, containing ASCC1, ASCC2, ASCC3, and TRIP4, and it also acts as a transcriptional coactivator.
How can I study the RQC-trigger complex?
Use Ribo-Seq, RNA-Seq, proteomics, and CRISPR knockout/knock-in models to dissect its function.
What is the role of TRIP4 in the RQC-trigger complex?
TRIP4 is a ribosome-interacting subunit that also functions as a transcriptional coactivator.
Is the RQC-trigger complex conserved?
Yes, it is conserved from yeast (RQT complex) to humans (ASC-1 complex).
What CRISPR models are available for RQC-trigger complex research?
EDITGENE offers knockout, point mutation, knock-in, overexpression, and library screening services for RQC-trigger complex genes.
Conclusion
The RQC-trigger complex (GO:0180022) is a critical cellular machine that maintains proteostasis by disassembling stalled ribosomes and extracting aberrant nascent polypeptides. Its dual role in translation quality control and transcriptional coactivation highlights its importance in health and disease. Continued research using advanced CRISPR models and multi-omics approaches will unravel its mechanistic details and therapeutic potential.
References
- 1. Inada T et al.. 2024. Mechanisms of Translation-coupled Quality Control.. J Mol Biol 436(6):168496 PMID: 38365086
- 2. Tomomatsu S et al.. 2025. Polyubiquitin architecture editing on collided ribosomes maintains persistent RQC activity.. EMBO J 44(21):6051-6077 PMID: 40957981
- 3. Matsuo Y et al.. 2020. RQT complex dissociates ribosomes collided on endogenous RQC substrate SDD1.. Nat Struct Mol Biol 27(4):323-332 PMID: 32203490
- 4. Hashimoto S et al.. 2020. Identification of a novel trigger complex that facilitates ribosome-associated quality control in mammalian cells.. Sci Rep 10(1):3422 PMID: 32099016
- 5. Miścicka A et al.. 2024. Ribosomal collision is not a prerequisite for ZNF598-mediated ribosome ubiquitination and disassembly of ribosomal complexes by ASCC.. Nucleic Acids Res 52(8):4627-4643 PMID: 38366554
- 6. Matsuo Y et al.. 2017. Ubiquitination of stalled ribosome triggers ribosome-associated quality control.. Nat Commun 8(1):159 PMID: 28757607
- 7. Mizuno M et al.. 2021. The nascent polypeptide in the 60S subunit determines the Rqc2-dependency of ribosomal quality control.. Nucleic Acids Res 49(4):2102-2113 PMID: 33511411
- 8. Egorov AA et al.. 2021. Ribo-Seq and RNA-Seq of TMA46 ( DFRP1) and GIR2 ( DFRP2) knockout yeast strains.. F1000Res 10:1162 PMID: 34900236
