GO:0034457 Mpp10 complex: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0034457 (Mpp10 complex) is a protein subcomplex of the 90S preribosome, composed in S. cerevisiae of Mpp10p, Imp3p and Imp4p.
• The Mpp10 complex is a platform that coordinates multiple factors within the 90S pre-ribosome during early ribosome biogenesis.
• Sas10 stabilizes Mpp10 and delivers the Mpp10-Imp3-Imp4 complex to the nucleolus, linking complex integrity to subcellular localization.
• The complex is functionally tied to the U3 small nucleolar RNP (snoRNP) and to small-subunit (SSU) processome assembly intermediates.
• Human scleroderma sera can contain autoantibodies to protein components specific to the U3 snoRNP complex, underscoring the clinical relevance of these proteins.
• CRISPR-based knockout, point-mutation, knock-in, tagged knock-in and overexpression models enable causal dissection of Mpp10 complex gene function.
Description
The Mpp10 complex (GO:0034457) is a cellular component defined as a protein complex that forms a subcomplex of the 90S preribosome; in S. cerevisiae it is composed of Mpp10p, Imp3p and Imp4p. This complex sits at the heart of early ribosome biogenesis, where the 90S preribosome matures into the small ribosomal subunit. Because the Mpp10 complex acts as a platform for the interaction of multiple factors within the 90S pre-ribosome, its composition and assembly are central to understanding how pre-rRNA processing is coordinated. Researchers study GO:0034457 because defects in ribosome biogenesis intersect with nucleolar organization, cell growth control and human disease. The complex is physically and functionally linked to the U3 small nucleolar RNP (snoRNP), a key player in early pre-rRNA cleavage events. Sas10 controls ribosome biogenesis by stabilizing Mpp10 and delivering the Mpp10-Imp3-Imp4 complex to the nucleolus, showing that complex stability and localization are regulated steps rather than passive events. From a methods standpoint, the Mpp10 complex can be interrogated by structural, biochemical and genetic approaches. Crystallization of Imp3 in complex with an Mpp10 peptide has provided direct structural insight into this interaction, while genetic and cell-biological studies have defined assembly intermediates that contain the U3 snoRNP, nucleolin, RRP5 and DBP4. Together, these studies make GO:0034457 a tractable and informative node for ribosome biogenesis research.
Mpp10 complex At A Glance
| GO ID | GO:0034457 |
|---|---|
| GO term | Mpp10 complex |
| Ontology | cellular_component |
| Synonym | None listed |
| Major function | Subcomplex of the 90S preribosome that acts as a platform for multiple factors during early ribosome biogenesis |
| Composition (S. cerevisiae) | Mpp10p, Imp3p and Imp4p |
| Localization | Nucleolus, delivered there via Sas10-dependent stabilization of Mpp10 |
| Related machinery | U3 small nucleolar RNP (snoRNP) and SSU processome assembly intermediates |
| Structural insight | Imp3 can be crystallized in complex with an Mpp10 peptide |
What Is GO:0034457?
GO:0034457 (Mpp10 complex) is a protein complex that forms a subcomplex of the 90S preribosome. In S. cerevisiae, it is composed of Mpp10p, Imp3p and Imp4p. The term is annotated to the cellular component ontology aspect. No synonyms are listed for this term. Functionally, the complex serves as a platform for the interaction of multiple factors within the 90S pre-ribosome, and its delivery to the nucleolus is promoted by Sas10, which stabilizes Mpp10.
Why Is Mpp10 complex Important in Cell Biology?
The Mpp10 complex is important because it is a core building block of the 90S preribosome, the machine that produces the small ribosomal subunit. Its role as a platform for multiple factors means that its integrity influences how pre-rRNA processing factors are assembled and positioned. Sas10-dependent stabilization and nucleolar delivery of the Mpp10-Imp3-Imp4 complex further show that the complex is a regulated hub rather than a static structural unit. Because the complex is linked to the U3 snoRNP and SSU processome intermediates, it is directly relevant to studies of ribosome biogenesis, nucleolar function and diseases in which these processes are perturbed.
Mpp10 complex (GO:0034457)
• Defines a specific subcomplex of the 90S preribosome required for early ribosome biogenesis.
• Provides a physical platform for multiple factors within the 90S pre-ribosome.
• Links Sas10 function to Mpp10 stability and nucleolar delivery of the Mpp10-Imp3-Imp4 complex.
• Connects to the U3 snoRNP, a central player in early pre-rRNA processing.
• Is part of SSU processome assembly intermediates containing nucleolin, RRP5 and DBP4.
• Has structural tractability, as shown by crystallization of Imp3 with an Mpp10 peptide.
• Is relevant to autoantibody responses against U3 snoRNP components in human scleroderma.
• Provides a genetic entry point for studying the transition of the t-Utp complex into the SSU processome.
• Supports mechanistic studies of nucleolar localization of the U3 snoRNP.
• Offers a defined target set for CRISPR knockout, point-mutation, knock-in and overexpression models.
What Happens During Mpp10 complex?
(未命名小节)
In simple terms: The Mpp10 complex helps build the small part of the ribosome by organizing other factors early in the process.
The Mpp10 complex functions within the 90S preribosome during early ribosome biogenesis. It forms a subcomplex composed in S. cerevisiae of Mpp10p, Imp3p and Imp4p. Within the 90S pre-ribosome, Mpp10 represents a platform for the interaction of multiple factors, meaning it helps bring together and position components needed for maturation. Sas10 controls ribosome biogenesis by stabilizing Mpp10 and delivering the Mpp10-Imp3-Imp4 complex to the nucleolus, so the complex must be both stable and correctly localized to function. The complex operates in the context of the U3 small nucleolar RNP and SSU processome assembly intermediates.
Assembly and delivery to the nucleolus
In simple terms: A helper protein called Sas10 keeps Mpp10 stable and carries the complex to the nucleolus, the cell's ribosome factory.
Sas10 controls ribosome biogenesis by stabilizing Mpp10 and delivering the Mpp10-Imp3-Imp4 complex to the nucleolus. This indicates that assembly of the Mpp10 complex is coupled to its subcellular targeting. The nucleolus is the site where the U3 snoRNP localizes and where pre-rRNA base pairing and 80S complex formation influence subnucleolar localization. Delivery of the Mpp10-Imp3-Imp4 complex to the nucleolus therefore places it where early ribosome biogenesis occurs.
Structure and Composition of Mpp10 complex
In simple terms: The complex is made of three proteins, and one of them, Imp3, can be studied together with a piece of Mpp10.
In S. cerevisiae, the Mpp10 complex is composed of Mpp10p, Imp3p and Imp4p. Structural work has advanced through purification, crystallization and preliminary X-ray diffraction analysis of Imp3 in complex with an Mpp10 peptide involved in yeast ribosome biogenesis. This provides direct structural evidence for the Imp3-Mpp10 interaction. The complex is a subcomplex of the 90S preribosome, and Mpp10 serves as a platform for the interaction of multiple factors within that larger particle.
Molecular Mechanism of Mpp10 complex
In simple terms: The complex does not cut RNA itself; it organizes other factors so that pre-rRNA processing can proceed correctly.
The Mpp10 complex acts as a platform for the interaction of multiple factors within the 90S pre-ribosome. Its mechanism is therefore organizational and structural rather than catalytic: it helps assemble and position factors required for early ribosome biogenesis. This function is closely tied to the U3 small nucleolar RNP, whose protein components are recognized by human scleroderma autoantibodies. The complex also participates in SSU processome assembly intermediates that contain the U3 snoRNP, nucleolin, RRP5 and DBP4, and it is connected to the transition of the t-Utp complex into the SSU processome.
Relationship to the U3 snoRNP and SSU processome
In simple terms: The Mpp10 complex works alongside the U3 snoRNP and the SSU processome, which together prepare the small ribosomal subunit.
The Mpp10 complex is functionally linked to the U3 small nucleolar RNP. Human scleroderma sera contain autoantibodies to protein components specific to the U3 small nucleolar RNP complex. A novel small-subunit processome assembly intermediate contains the U3 snoRNP, nucleolin, RRP5 and DBP4, and pre-rRNA base pairing and 80S complex formation influence subnucleolar localization of the U3 snoRNP. Proteins and RNA sequences are required for the transition of the t-Utp complex into the SSU processome. These findings place the Mpp10 complex within a broader assembly pathway for the small ribosomal subunit.
Key Genes Involved in GO:0034457 Mpp10 complex
The following genes and proteins are directly or functionally associated with the Mpp10 complex and its role in early ribosome biogenesis, based on the verified literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| MPP10 (Mpp10p) | Core component of the Mpp10 complex; platform for multiple factors in the 90S pre-ribosome | Central to GO:0034457 definition and to 90S preribosome function |
| IMP3 (Imp3p) | Core component of the Mpp10 complex; structurally characterized with an Mpp10 peptide | Provides structural insight into complex assembly |
| IMP4 (Imp4p) | Core component of the Mpp10 complex | Defines the three-protein composition in S. cerevisiae |
| SAS10 (Sas10) | Stabilizes Mpp10 and delivers the Mpp10-Imp3-Imp4 complex to the nucleolus | Links complex stability to nucleolar localization |
| UTP proteins (t-Utp complex) | Required for transition into the SSU processome | Connects early assembly steps to the Mpp10 complex pathway |
| Nucleolin | Component of an SSU processome assembly intermediate | Marks an intermediate containing the U3 snoRNP |
| RRP5 | Component of an SSU processome assembly intermediate | Marks an intermediate containing the U3 snoRNP |
| DBP4 | Component of an SSU processome assembly intermediate | Marks an intermediate containing the U3 snoRNP |
| U3 snoRNA | RNA component of the U3 snoRNP | Central to early pre-rRNA processing and subnucleolar localization |
| U3 snoRNP proteins | Protein components specific to the U3 snoRNP | Targets of autoantibodies in human scleroderma |
| CAPN3 | Forms a nucleolus-localized Def-CAPN3 complex via an 86 amino acid motif | Provides a nucleolar complex context relevant to nucleolar biology |
| Def (CAPN3 partner) | Partners with CAPN3 in the Def-CAPN3 complex | Nucleolar complex formation model |
How Is Mpp10 complex Regulated?
The Mpp10 complex is regulated at the level of stability and localization. Sas10 controls ribosome biogenesis by stabilizing Mpp10 and delivering the Mpp10-Imp3-Imp4 complex to the nucleolus, which means that Sas10 availability or function can influence how much functional complex reaches the nucleolus. Subnucleolar localization of the U3 snoRNP depends on pre-rRNA base pairing and 80S complex formation, indicating that the localization of U3 snoRNP-associated machinery is coupled to ribosome assembly status. The transition of the t-Utp complex into the SSU processome requires specific proteins and RNA sequences, adding a further layer of regulation to the assembly pathway in which the Mpp10 complex operates.
Mpp10 complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| U3 snoRNP protein components | Autoantibody response in human scleroderma | Knockout or tagged knock-in of U3 snoRNP component genes followed by autoantibody profiling |
| MPP10 | Early ribosome biogenesis and 90S preribosome function | Point-mutation or knockout models to test Mpp10 stability and nucleolar delivery |
| SAS10 | Mpp10 stabilization and nucleolar delivery | Knockout and rescue with tagged Sas10 to monitor Mpp10-Imp3-Imp4 localization |
| IMP3 | Structural basis of Mpp10 complex assembly | Point-mutation models guided by the Imp3-Mpp10 peptide crystal structure |
| CAPN3 | Nucleolus-localized Def-CAPN3 complex formation | Knock-in or point-mutation models of the 86 amino acid motif |
Autoimmunity and scleroderma
Human scleroderma sera contain autoantibodies to protein components specific to the U3 small nucleolar RNP complex. Because the Mpp10 complex is functionally linked to the U3 snoRNP in early ribosome biogenesis, these autoantibodies highlight a clinical connection between U3 snoRNP-associated machinery and autoimmune disease. This makes U3 snoRNP components, including those related to the Mpp10 complex, relevant to studies of autoantibody profiles in scleroderma.
Ribosome biogenesis and nucleolar dysfunction
The Mpp10 complex is a subcomplex of the 90S preribosome and acts as a platform for multiple factors during early ribosome biogenesis. Disruption of early ribosome biogenesis steps, including the transition of the t-Utp complex into the SSU processome, can affect small-subunit production. Because nucleolar localization of the U3 snoRNP depends on pre-rRNA base pairing and 80S complex formation, perturbations in these processes are expected to impact nucleolar organization and ribosome output.
Nucleolar complex biology and disease-relevant pathways
An 86 amino acid motif in CAPN3 is essential for formation of the nucleolus-localized Def-CAPN3 complex. This finding illustrates that nucleolus-localized complexes can depend on defined protein motifs, a principle that is also relevant to understanding how the Mpp10 complex is assembled and delivered to the nucleolus via Sas10. Studying such motifs and interactions can inform models of nucleolar dysfunction in disease.
From Mpp10 complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is Mpp10 required for 90S preribosome function? | CRISPR knockout of MPP10 with growth and pre-rRNA processing readouts |
| How does Sas10 stabilize Mpp10? | Knockout of SAS10 plus tagged knock-in of MPP10 to follow stability and localization |
| Which Imp3 residues contact Mpp10? | Point-mutation of IMP3 based on the Imp3-Mpp10 peptide crystal structure |
| Where does the Mpp10-Imp3-Imp4 complex localize? | Tagged knock-in of complex components for nucleolar imaging |
| Does overexpression of complex components alter ribosome biogenesis? | Overexpression of MPP10, IMP3 or IMP4 with ribosome biogenesis assays |
| How does the t-Utp complex transition into the SSU processome? | Knockout or point-mutation of transition factors with assembly intermediate analysis |
How to Study the Mpp10 complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| X-ray crystallography | Atomic structure of protein-peptide complexes | Imp3 in complex with an Mpp10 peptide |
| Affinity purification | Protein-protein interactions and complex composition | Isolating Mpp10-Imp3-Imp4 and associated factors |
| Fluorescence imaging | Subcellular and subnucleolar localization | Tracking nucleolar delivery of the Mpp10-Imp3-Imp4 complex |
| Genetic perturbation | Requirement of genes and RNA sequences for assembly | Testing t-Utp to SSU processome transition |
| Assembly intermediate analysis | Composition of preribosome intermediates | Characterizing U3 snoRNP-containing SSU processome intermediates |
| Autoantibody profiling | Immune recognition of U3 snoRNP proteins | Scleroderma serum screening |
| Motif mapping | Protein domains required for complex formation | Defining motifs such as the CAPN3 86 amino acid motif |
Structural and biochemical analysis
Purification, crystallization and preliminary X-ray diffraction analysis of Imp3 in complex with an Mpp10 peptide has been used to study the physical interaction underlying yeast ribosome biogenesis. This approach defines the molecular interface between core components of the Mpp10 complex and can guide point-mutation design.
Assembly intermediate profiling
A novel small-subunit processome assembly intermediate containing the U3 snoRNP, nucleolin, RRP5 and DBP4 has been characterized, providing a framework for mapping where the Mpp10 complex acts. Proteins and RNA sequences required for the transition of the t-Utp complex into the SSU processome can be identified by genetic and biochemical perturbation.
Nucleolar localization imaging
Subnucleolar localization of the U3 snoRNP depends on pre-rRNA base pairing and 80S complex formation, making imaging of nucleolar markers informative for Mpp10 complex studies. Sas10-dependent delivery of the Mpp10-Imp3-Imp4 complex to the nucleolus can be monitored by tagging complex components and tracking their nucleolar enrichment.
Autoantibody and clinical profiling
Human scleroderma sera contain autoantibodies to protein components specific to the U3 small nucleolar RNP complex, which supports the use of patient sera to probe U3 snoRNP-associated proteins. Such profiling can complement mechanistic studies of the Mpp10 complex and its partners.
How CRISPR Can Be Used to Study GO:0034457 Mpp10 complex
Knockout
CRISPR knockout of MPP10, IMP3, IMP4 or SAS10 can test the requirement of each component for Mpp10 complex function and for early ribosome biogenesis. Because Sas10 stabilizes Mpp10 and delivers the Mpp10-Imp3-Imp4 complex to the nucleolus, SAS10 knockout models are particularly useful for separating stability from localization defects.
Point Mutation
Point mutations can be introduced into IMP3 at residues implicated in the Imp3-Mpp10 interface, guided by the crystal structure of Imp3 in complex with an Mpp10 peptide. Such models allow precise testing of which contacts are required for Mpp10 complex assembly and function.
Knock-in
Tagged knock-in of MPP10, IMP3 or IMP4 enables direct tracking of the Mpp10-Imp3-Imp4 complex and its nucleolar delivery. Knock-in approaches can also be used to introduce disease-relevant or motif-specific variants, such as those informed by the CAPN3 86 amino acid motif study.
Overexpression
Overexpression of MPP10, IMP3 or IMP4 can test whether excess complex components alter 90S preribosome function or nucleolar organization. Overexpression models are also useful for epistasis experiments with Sas10 and other assembly factors.
How EDITGENE Supports Mpp10 complex Research
Researchers studying Mpp10 complex-related genes often need to determine whether a candidate gene is causally involved in 90S preribosome function, nucleolar delivery or pre-rRNA processing, rather than merely correlated with these processes. CRISPR-based models provide the causal leverage needed to move from association to mechanism.
Contact EDITGENE today to design your custom CRISPR model for Mpp10 complex research.
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Frequently Asked Questions About Mpp10 complex
What is the Mpp10 complex?
The Mpp10 complex (GO:0034457) is a protein complex that forms a subcomplex of the 90S preribosome; in S. cerevisiae it is composed of Mpp10p, Imp3p and Imp4p.
What genes are involved in the Mpp10 complex?
In S. cerevisiae the core components are MPP10, IMP3 and IMP4, and Sas10 regulates the complex by stabilizing Mpp10 and delivering it to the nucleolus.
Where is the Mpp10 complex located?
It is delivered to the nucleolus via Sas10-dependent stabilization of Mpp10, placing it where early ribosome biogenesis occurs.
What does the Mpp10 complex do?
It acts as a platform for the interaction of multiple factors within the 90S pre-ribosome during early ribosome biogenesis.
How is the Mpp10 complex related to the U3 snoRNP?
The complex is functionally linked to the U3 small nucleolar RNP, and human scleroderma sera contain autoantibodies to U3 snoRNP protein components.
What is the structure of the Mpp10 complex?
Imp3 has been purified, crystallized and analyzed by X-ray diffraction in complex with an Mpp10 peptide, providing structural insight into the interaction.
Is the Mpp10 complex involved in disease?
U3 snoRNP protein components are targets of autoantibodies in human scleroderma, linking this machinery to autoimmune disease.
How can I study the Mpp10 complex with CRISPR?
Knockout, point-mutation, knock-in, tagged knock-in and overexpression models can be used to test component requirements, interfaces and localization.
What methods are used to study the Mpp10 complex?
Common approaches include crystallization, affinity purification, imaging of nucleolar localization, genetic perturbation and assembly intermediate analysis.
Why is the Mpp10 complex important for ribosome biogenesis?
It is a subcomplex of the 90S preribosome and a platform for multiple factors, and its delivery to the nucleolus is required for early ribosome biogenesis.
Conclusion
The Mpp10 complex (GO:0034457) is a defined subcomplex of the 90S preribosome composed in S. cerevisiae of Mpp10p, Imp3p and Imp4p. Its role as a platform for multiple factors, together with Sas10-dependent stabilization and nucleolar delivery, positions it as a key node in early ribosome biogenesis. Structural, genetic and cell-biological studies continue to clarify how this complex and its associated U3 snoRNP machinery function. For researchers, the Mpp10 complex offers a focused entry point into ribosome biogenesis, nucleolar organization and disease-relevant autoantibody responses. CRISPR-based knockout, point-mutation, knock-in and overexpression models make it possible to test causal roles of MPP10, IMP3, IMP4 and SAS10 in these processes.
References
- 1. Zhao S et al.. 2019. Sas10 controls ribosome biogenesis by stabilizing Mpp10 and delivering the Mpp10-Imp3-Imp4 complex to nucleolus.. Nucleic Acids Res 47(6):2996-3012 PMID: 30773582
- 2. Zheng S et al.. 2014. Purification, crystallization and preliminary X-ray diffraction analysis of Imp3 in complex with an Mpp10 peptide involved in yeast ribosome biogenesis.. Acta Crystallogr F Struct Biol Commun 70(Pt 7):918-21 PMID: 25005089
- 3. Sá-Moura B et al.. 2017. Mpp10 represents a platform for the interaction of multiple factors within the 90S pre-ribosome.. PLoS One 12(8):e0183272 PMID: 28813493
- 4. Yang JM et al.. 2003. Human scleroderma sera contain autoantibodies to protein components specific to the U3 small nucleolar RNP complex.. Arthritis Rheum 48(1):210-7 PMID: 12528121
- 5. Turner AJ et al.. 2009. A novel small-subunit processome assembly intermediate that contains the U3 snoRNP, nucleolin, RRP5, and DBP4.. Mol Cell Biol 29(11):3007-17 PMID: 19332556
- 6. Granneman S et al.. 2004. Role of pre-rRNA base pairing and 80S complex formation in subnucleolar localization of the U3 snoRNP.. Mol Cell Biol 24(19):8600-10 PMID: 15367679
- 7. Gallagher JEG. 2019. Proteins and RNA sequences required for the transition of the t-Utp complex into the SSU processome.. FEMS Yeast Res 19(1) PMID: 30445532
- 8. Ding F et al.. 2022. An 86 amino acids motif in CAPN3 is essential for formation of the nucleolus-localized Def-CAPN3 complex.. Biochem Biophys Res Commun 623:66-73 PMID: 35878425
