GO:0031475 myosin V complex: Components, Assembly and Research Methods, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0031475 myosin V complex is a cellular component defined as a dimeric myosin motor complex that mediates intracellular transport.
• The complex consists of two class V myosin heavy chains, each with a conserved motor domain, six IQ motifs that bind light chains and calmodulin, and a tail domain for cargo binding and localization.
• Myosin V complex moves cargo along actin filaments and is essential for short-range vesicle transport, including synaptic vesicle trafficking and receptor recycling.
• Cargo adaptors engage myosin V via a handhold mechanism to ensure efficient organelle transport.
• Dysregulation of myosin V complex components is linked to neurological disorders and cancer, making it a target for CRISPR-based disease modeling.
• Research methods include knockout, knock-in, overexpression, live-cell imaging, and proteomics to dissect myosin V complex function.
Description
The myosin V complex (GO:0031475) is a cellular component that functions as a dimeric motor protein complex responsible for intracellular transport along actin filaments. It is a member of the myosin superfamily, characterized by a conserved motor domain that hydrolyzes ATP to generate force and movement. The complex is particularly enriched in neurons and melanocytes, where it transports vesicles, organelles, and mRNA. Understanding the myosin V complex is critical because defects in its components are associated with human diseases, including neurological disorders and pigmentation defects. Moreover, myosin V complex serves as a model system for studying cargo recognition and motor regulation. Recent studies have elucidated the structural basis of cargo binding and the coordination between myosin V and actin assembly. This article provides a comprehensive overview of the myosin V complex, covering its definition, structure, function, regulation, disease relevance, and research methodologies, with a focus on CRISPR-based approaches for functional interrogation.
myosin V complex At A Glance
| GO ID | GO:0031475 |
|---|---|
| GO term | myosin V complex |
| Ontology | cellular_component |
| Synonym | None |
| Major function | Intracellular transport along actin filaments |
| Definition | A myosin complex containing a dimer of class V myosin heavy chains and associated light chains; involved in intracellular transport. |
| Composition | Dimer of class V myosin heavy chains, light chains, calmodulin |
| Cellular location | Cytoplasm, actin cytoskeleton, vesicle membranes |
| Associated processes | Vesicle transport, receptor recycling, synaptic vesicle trafficking |
What Is GO:0031475?
The myosin V complex is a cellular component defined by the Gene Ontology as a myosin complex containing a dimer of class V myosin heavy chains and associated light chains, involved in intracellular transport. Myosin V is a dimeric molecule consisting of conserved motor domains followed by six IQ motifs which bind specific light chains and calmodulin. The tail domain is important for cellular localization and cargo binding and can be divided into an alpha-helical coiled coil region and a C-terminal globular region.
Why Is myosin V complex Important in Cell Biology?
The myosin V complex is essential for intracellular transport, a fundamental process that ensures proper distribution of organelles, vesicles, and macromolecules within cells. Its dysfunction has been linked to neurological disorders, such as Griscelli syndrome and microvillus inclusion disease, as well as cancer progression. Studying the myosin V complex provides insights into motor protein mechanics, cargo recognition, and cytoskeletal regulation. Furthermore, the complex is a target for therapeutic intervention, and CRISPR-based models can help elucidate its role in disease.
• Mediates short-range vesicle transport in neurons and other cell types.
• Required for efficient receptor recycling and synaptic vesicle trafficking.
• Mutations in myosin V heavy chain genes cause Griscelli syndrome and neurological defects.
• Involved in melanosome transport and pigmentation.
• Cargo adaptors regulate myosin V function via a handhold mechanism.
• Coordinates with actin assembly for efficient transport.
• Potential target for cancer therapy due to role in cell migration and invasion.
• Essential for intracellular transport of LDL receptor and cholesterol uptake.
• Regulated by calcium/calmodulin and phosphorylation.
• CRISPR screens can identify novel regulators of myosin V complex function.
Core Biology of the myosin V complex
What Happens During myosin V complex-mediated Transport?
In simple terms: The myosin V complex acts like a molecular truck that carries cargo along actin tracks inside cells.
The myosin V complex mediates the transport of various cargoes, including vesicles, organelles, and mRNA, along actin filaments. The process begins with cargo binding to the tail domain of myosin V, often via adaptor proteins. ATP hydrolysis by the motor domain drives conformational changes that allow the complex to 'walk' along actin filaments in a hand-over-hand manner. This transport is crucial for short-range vesicle movement, such as synaptic vesicle trafficking in neurons and receptor recycling. The complex also interacts with Rab GTPases, such as Rab10, to facilitate vesicle transport to migrasomes.
Structure and Composition of the myosin V complex
In simple terms: The myosin V complex is made of two heavy chains that intertwine, with light chains attached and a tail that holds cargo.
The myosin V complex is a dimer of class V myosin heavy chains, each consisting of a conserved N-terminal motor domain, six IQ motifs that bind light chains and calmodulin, a coiled-coil region for dimerization, and a C-terminal globular tail domain for cargo binding. The heavy chains are encoded by genes such as MYO5A, MYO5B, and MYO5C in humans. Light chains include calmodulin and myosin light chains, which regulate motor activity in a calcium-dependent manner. The tail domain interacts with cargo adaptors like melanophilin and Rab11-FIP2.
Molecular Mechanism of myosin V complex
In simple terms: The myosin V motor uses ATP energy to move along actin, with calcium and light chains controlling its activity.
The molecular mechanism of myosin V involves ATP binding and hydrolysis in the motor domain, which causes a conformational change that propels the motor along actin filaments. The IQ motifs bind calmodulin and light chains, which sense calcium levels and regulate motor activity. The tail domain binds cargo directly or via adaptors, and its phosphorylation can regulate cargo release. Recent studies have revealed a 'handhold' mechanism where cargo adaptors engage myosin V to ensure processive transport. Additionally, myosin V function is coordinated with actin assembly factors to facilitate transport through dense cytoskeletal networks.
Regulation of myosin V complex Activity
In simple terms: The myosin V complex is switched on and off by calcium signals and phosphorylation.
Myosin V complex activity is regulated by calcium/calmodulin binding to the IQ motifs, which can inhibit or activate motor function depending on calcium concentration. Phosphorylation of the heavy chain or light chains can also modulate activity and cargo binding. For example, phosphorylation of the tail domain by kinases such as CaMKII can affect cargo release. Rab GTPases and their effectors, such as Rab10, regulate the recruitment of myosin V to specific vesicles. Moreover, the complex is regulated by interactions with actin-binding proteins and cargo adaptors.
Key Genes Involved in GO:0031475 myosin V complex
The following genes encode components or regulators of the myosin V complex and are commonly studied in research.
| Gene | Major Role | Research Relevance |
|---|---|---|
| MYO5A | Encodes myosin VA heavy chain; motor and cargo binding | Mutations cause Griscelli syndrome and neurological disorders |
| MYO5B | Encodes myosin VB heavy chain; epithelial transport | Linked to microvillus inclusion disease |
| MYO5C | Encodes myosin VC heavy chain; transport in specialized cells | Less studied; potential role in secretion |
| CALM1 | Calmodulin; binds IQ motifs and regulates motor | Calcium-dependent regulation of myosin V |
| CALM2 | Calmodulin; binds IQ motifs and regulates motor | Calcium-dependent regulation of myosin V |
| CALM3 | Calmodulin; binds IQ motifs and regulates motor | Calcium-dependent regulation of myosin V |
| MYL6 | Myosin light chain; binds IQ motifs | Regulates motor activity |
| RAB10 | Rab GTPase; regulates vesicle transport | Mediates intraluminal vesicle transport to migrasomes |
| RAB11A | Rab GTPase; regulates recycling endosomes | Interacts with myosin V for receptor recycling |
| RAB27A | Rab GTPase; regulates melanosome transport | Mutations cause Griscelli syndrome |
| MLPH | Melanophilin; cargo adaptor for myosin Va | Links myosin Va to melanosomes |
| MYRIP | Myosin VIIA and Rab interacting protein; adaptor | Involved in retinal transport |
| LIMA1 | LIM domain and actin binding 1; regulates actin | Variant affects cholesterol absorption via myosin V? |
| CAV1 | Caveolin-1; membrane protein | Involved in Rab10-mediated transport |
| SYT1 | Synaptotagmin 1; synaptic vesicle protein | Interacts with myosin V in neurons |
| VAMP2 | Synaptobrevin 2; synaptic vesicle protein | Ca2+-dependent interaction with myosin V |
| SYP | Synaptophysin; synaptic vesicle protein | Forms complex with myosin V |
How Is myosin V complex Regulated?
The myosin V complex is regulated at multiple levels. Calcium/calmodulin binding to the IQ motifs modulates motor activity, with high calcium inhibiting processive movement. Phosphorylation of the heavy chain or light chains by kinases such as CaMKII can alter cargo binding and motor function. Rab GTPases, including Rab10 and Rab11, regulate the recruitment of myosin V to specific vesicle populations. Cargo adaptors such as melanophilin and Rab11-FIP2 mediate the interaction between myosin V and cargo, and their phosphorylation can regulate cargo release. Additionally, the complex is regulated by interactions with actin assembly factors, which coordinate transport with cytoskeletal dynamics.
myosin V complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| MYO5A | Griscelli syndrome type 1; neurological defects | Knockout mouse; patient-derived iPSCs |
| MYO5B | Microvillus inclusion disease | Intestinal organoids; CRISPR knock-in |
| RAB27A | Griscelli syndrome type 2 | Knockout mouse; melanocyte cultures |
| MLPH | Griscelli syndrome type 3 | Knockout mouse; melanocyte cultures |
| MYO5C | Potential role in cancer | Overexpression cell lines; xenograft models |
Myosin V complex in Neurological Disorders
Mutations in MYO5A cause Griscelli syndrome type 1, characterized by hypopigmentation and severe neurological impairment. Myosin Va is enriched in neurons and is essential for synaptic vesicle trafficking and receptor recycling. Dysfunction of myosin V complex has been implicated in other neurological conditions, including schizophrenia and bipolar disorder, although the exact mechanisms remain under investigation. Studies using knockout mouse models have revealed roles in memory and learning.
Myosin V complex in Cancer
Myosin V complex components are involved in cell migration, invasion, and metastasis. MYO5A overexpression has been observed in some cancers and is associated with poor prognosis. The complex facilitates the transport of matrix metalloproteinases and integrins to the cell surface, promoting invasion. Targeting myosin V complex with small molecules or CRISPR-based knockout could be a therapeutic strategy.
Myosin V complex in Pigmentation and Epithelial Disorders
Mutations in MYO5A or its adaptor MLPH cause Griscelli syndrome type 3, characterized by hypopigmentation without neurological defects. MYO5B mutations are linked to microvillus inclusion disease, a congenital enteropathy with severe diarrhea. These disorders highlight the critical role of myosin V complex in melanosome transport and epithelial cell polarity.
From myosin V complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does MYO5A loss affect synaptic vesicle transport? | MYO5A knockout neurons |
| Does a point mutation in MYO5A affect motor activity? | Knock-in mice or cell lines with specific mutation |
| How does cargo adaptor binding regulate myosin V? | Tagged knock-in of MLPH or RAB11A |
| Can overexpression of MYO5A drive cancer invasion? | MYO5A overexpression in cancer cell lines |
| What is the role of MYO5B in epithelial polarity? | MYO5B knockout intestinal organoids |
| Does Rab10 regulate myosin V-mediated migrasome formation? | RAB10 knockout cells; live imaging |
How to Study the myosin V complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Live-cell imaging | Real-time transport dynamics | Visualizing myosin V cargo movement |
| TIRF microscopy | Single-molecule stepping | Motor mechanism studies |
| Immunoprecipitation + mass spectrometry | Protein interactions | Identifying novel cargo adaptors |
| CRISPR knockout screens | Gene function in transport | Discovering regulators of migrasome formation |
| In vitro motility assay | Motor velocity and processivity | Testing mutant myosin V activity |
| ATPase assay | Enzymatic activity | Measuring motor domain function |
| Proximity ligation assay | Protein-protein interactions in situ | Validating cargo-adaptor binding |
| RNA-seq | Transcriptional changes | Assessing knockout effects on transport genes |
Live-cell Imaging of Myosin V Transport
Live-cell imaging using fluorescently tagged myosin V and cargo proteins allows real-time visualization of transport dynamics. Total internal reflection fluorescence (TIRF) microscopy can resolve single-molecule stepping. This method is essential for understanding how cargo adaptors engage myosin V.
Proteomic Analysis of Myosin V Complex
Affinity purification coupled with mass spectrometry can identify novel components and cargo adaptors of the myosin V complex. For example, immunoprecipitation of myosin Va from brain lysates revealed interactions with synaptobrevin and synaptophysin. Proteomics can also reveal post-translational modifications that regulate the complex.
CRISPR Screening for Regulators of Myosin V Function
Genome-wide CRISPR knockout screens can identify genes required for myosin V-mediated transport. For instance, a screen for regulators of migrasome formation identified Rab10 and CAV1 as critical components. Such screens can uncover new therapeutic targets.
Biochemical Assays for Motor Activity
In vitro motility assays and ATPase assays measure the motor activity of purified myosin V. These assays can be used to test the effect of mutations or regulatory proteins. They provide quantitative data on velocity and processivity.
How CRISPR Can Be Used to Study GO:0031475 myosin V complex
Knockout
CRISPR knockout of MYO5A, MYO5B, or MYO5C can abolish myosin V complex function, leading to defects in vesicle transport and cellular organization. Knockout cell lines are valuable for studying the loss-of-function phenotypes and for identifying compensatory mechanisms. For example, MYO5A knockout neurons show impaired synaptic vesicle trafficking.
Point Mutation
CRISPR point mutation can introduce disease-associated mutations, such as those found in Griscelli syndrome, to study their effects on motor activity and cargo binding. This approach allows precise modeling of human genetic variants. For instance, a point mutation in the motor domain can impair ATP hydrolysis.
Knock-in
Knock-in of tagged myosin V (e.g., GFP or HaloTag) enables live-cell imaging and proteomic analysis of the complex. Knock-in of cargo adaptors with tags can reveal their dynamic interactions. This method is also used to create reporter cell lines for high-throughput screening.
Overexpression
Overexpression of myosin V or its cargo adaptors can reveal gain-of-function phenotypes, such as increased transport or altered localization. Overexpression in cancer cell lines can promote invasion and metastasis. This approach is useful for studying the effects of elevated motor protein levels.
How EDITGENE Supports myosin V complex Research
Researchers studying myosin V complex-related genes often need to determine whether a candidate gene is causally involved in transport, disease, or cellular homeostasis. EDITGENE provides a comprehensive suite of CRISPR services to enable precise genetic interrogation of the myosin V complex and its regulators.
Contact EDITGENE today to design your custom CRISPR model for myosin V complex research.
Frequently Asked Questions About myosin V complex
What is the myosin V complex?
The myosin V complex is a dimeric motor protein complex that transports cargo along actin filaments, defined by GO:0031475.
What genes are involved in the myosin V complex?
Key genes include MYO5A, MYO5B, MYO5C, CALM1/2/3, and adaptors like MLPH and RAB27A.
What is the function of myosin V complex?
It mediates intracellular transport of vesicles, organelles, and mRNA, and is involved in synaptic vesicle trafficking and receptor recycling.
How is myosin V complex regulated?
It is regulated by calcium/calmodulin, phosphorylation, and Rab GTPases.
What diseases are associated with myosin V complex?
Mutations cause Griscelli syndrome, microvillus inclusion disease, and neurological disorders; it is also implicated in cancer.
What is the structure of myosin V complex?
It consists of two heavy chains, each with a motor domain, six IQ motifs, a coiled-coil region, and a globular tail domain.
How can I study myosin V complex using CRISPR?
CRISPR knockout, knock-in, point mutation, and overexpression models can be used to dissect its function.
What is the role of myosin V in neurons?
Myosin V transports synaptic vesicles and is essential for neurotransmitter release and receptor recycling.
What is the handhold mechanism in myosin V transport?
Cargo adaptors use a handhold mechanism to engage myosin V, ensuring efficient organelle transport.
What research methods are used to study myosin V complex?
Live-cell imaging, proteomics, CRISPR screens, and biochemical assays are commonly used.
Conclusion
The myosin V complex (GO:0031475) is a critical molecular motor for intracellular transport, with essential roles in neuronal function, pigmentation, and epithelial polarity. Its dysfunction leads to severe human diseases, and ongoing research continues to uncover its regulatory mechanisms and cargo interactions. CRISPR-based models offer powerful tools to dissect the complex's function and identify therapeutic targets. EDITGENE provides comprehensive CRISPR services to support these studies.
References
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- 3. Langford GM. 2002. Myosin-V, a versatile motor for short-range vesicle transport.. Traffic 3(12):859-65 PMID: 12453149
- 4. Zhang YY et al.. 2018. A LIMA1 variant promotes low plasma LDL cholesterol and decreases intestinal cholesterol absorption.. Science 360(6393):1087-1092 PMID: 29880681
- 5. Hahn HJ et al.. 2025. Cargo adaptors use a handhold mechanism to engage with myosin V for organelle transport.. J Cell Biol 224(7) PMID: 40377475
- 6. Welz T et al.. 2019. Exploring the iceberg: Prospects of coordinated myosin V and actin assembly functions in transport processes.. Small GTPases 10(2):111-121 PMID: 28394692
- 7. Yan Q et al.. 2005. CART: an Hrs/actinin-4/BERP/myosin V protein complex required for efficient receptor recycling.. Mol Biol Cell 16(5):2470-82 PMID: 15772161
- 8. Prekeris R et al.. 1997. Brain myosin V is a synaptic vesicle-associated motor protein: evidence for a Ca2+-dependent interaction with the synaptobrevin-synaptophysin complex.. J Cell Biol 137(7):1589-601 PMID: 9199173
