GO:0098826 endoplasmic reticulum tubular network membrane: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0098826 defines the membrane of the endoplasmic reticulum tubular network, a curved, high-surface-area compartment distinct from ER sheets.
• The tubular ER network is shaped by membrane proteins including reticulons and DP1/Yop1p, which stabilize high membrane curvature.
• Reconstitution with purified components shows that reticulons, atlastin, and lunapark are sufficient to generate and maintain tubular ER networks in vitro.
• Atlastin-mediated GTP-dependent fusion and lunapark-mediated ubiquitination of atlastin-2 regulate tubular network formation and connectivity.
• Dysferlin enables tubular membrane proliferation in cardiac hypertrophy, linking GO:0098826 to dynamic membrane remodeling in disease.
• ER-to-Golgi protein delivery occurs through an interwoven tubular network extending from the ER, highlighting the functional importance of tubular ER membrane organization.
Description
The endoplasmic reticulum (ER) is a continuous membrane system that includes both sheet-like and tubular domains. The tubular network membrane, annotated as GO:0098826, is the membrane surrounding the ER tubular network, a compartment characterized by high curvature and a branched, interconnected architecture. This membrane domain is essential for diverse cellular functions, including lipid synthesis, calcium storage, and protein trafficking. Understanding the molecular composition and assembly of the tubular ER membrane is critical for researchers studying organelle biogenesis, membrane dynamics, and related diseases. The tubular ER network is not a static structure; it undergoes constant remodeling driven by membrane-shaping proteins and fusion events. Recent advances in reconstitution and imaging have begun to reveal how specific proteins generate and maintain this membrane domain. This article synthesizes current knowledge on GO:0098826, covering its definition, key protein components, regulatory mechanisms, disease relevance, and experimental approaches for investigation.
endoplasmic reticulum tubular network membrane At A Glance
| GO ID | GO:0098826 |
|---|---|
| GO term | endoplasmic reticulum tubular network membrane |
| Ontology | cellular_component |
| Synonym | none |
| Major function | Forms the curved membrane boundary of the ER tubular network, enabling lipid and protein dynamics, calcium signaling, and organelle connectivity. |
| Key structural proteins | Reticulons (RTN1-4), DP1/Yop1p, atlastin-1/2/3, lunapark, dysferlin. |
| Assembly mechanism | Membrane curvature stabilization by reticulons and DP1/Yop1p; fusion by atlastin GTPases; regulation by lunapark-mediated ubiquitination. |
| Associated processes | ER-to-Golgi protein delivery, membrane fusion, calcium homeostasis, lipid synthesis. |
| Disease links | Hereditary spastic paraplegia (atlastin-1 mutations), cardiac hypertrophy (dysferlin), platelet ultrastructure. |
What Is GO:0098826?
GO:0098826, endoplasmic reticulum tubular network membrane, is defined as the membrane of the endoplasmic reticulum tubular network. In other words, it is the lipid bilayer that encloses the tubular portion of the ER, excluding the sheet-like regions. This membrane domain is characterized by high curvature and a distinct set of embedded and associated proteins that shape and maintain its tubular morphology.
Why Is endoplasmic reticulum tubular network membrane Important in Cell Biology?
The endoplasmic reticulum tubular network membrane (GO:0098826) is a central hub for cellular organization and communication. It provides a platform for lipid and protein synthesis, facilitates calcium storage and release, and serves as the origin for ER-to-Golgi transport carriers. Dysregulation of tubular ER membrane proteins is linked to human diseases, including hereditary spastic paraplegia and cardiac hypertrophy. Moreover, the tubular ER network is dynamically remodeled during cell division, differentiation, and stress responses, making it a key area of research in cell biology and pathology.
• Provides a high-surface-area membrane platform for lipid synthesis and calcium signaling.
• Essential for ER-to-Golgi protein delivery through interwoven tubular networks.
• Mutations in atlastin-1, a tubular ER fusion GTPase, cause hereditary spastic paraplegia.
• Dysferlin-mediated tubular membrane proliferation occurs in cardiac hypertrophy.
• Platelet ultrastructure and production depend on tubular ER membrane dynamics.
• Reconstitution studies reveal minimal components sufficient for tubular network formation.
• Lunapark regulates atlastin-2 ubiquitination to control tubular network formation.
• Membrane-shaping proteins like reticulons are conserved from yeast to humans.
• Tubular ER membrane nanostructures are shaped by protein-lipid interactions.
• The tubular ER network is a target for understanding organelle biogenesis and disease mechanisms.
What Happens During endoplasmic reticulum tubular network membrane?
Membrane Curvature Stabilization by Reticulons and DP1/Yop1p
In simple terms: Special proteins insert into the membrane and bend it into tubes.
The tubular ER network is shaped by a class of membrane proteins including reticulons and DP1/Yop1p. These proteins contain hydrophobic hairpin domains that insert into the membrane and stabilize high curvature, generating and maintaining the tubular morphology. Their abundance and distribution determine the ratio of tubular to sheet-like ER.
Atlastin-Mediated Membrane Fusion
In simple terms: Atlastin proteins connect tubes by fusing them together.
Atlastin GTPases (atlastin-1, -2, -3 in mammals) mediate homotypic fusion of ER tubules. GTP hydrolysis drives a conformational change that pulls membranes together, enabling lipid bilayer merger and network formation. This fusion activity is essential for maintaining a continuous tubular network.
Lunapark Regulation of Atlastin-2
In simple terms: Lunapark tags atlastin-2 with ubiquitin to control tube formation.
Lunapark is a membrane protein that ubiquitinates atlastin-2, modulating its activity and stability. This ubiquitination is required for proper tubular network formation, as loss of lunapark leads to aberrant ER morphology. Thus, lunapark acts as a regulator of atlastin-mediated fusion.
Dysferlin-Mediated Tubular Membrane Proliferation
In simple terms: Dysferlin helps grow more tubular membrane during heart enlargement.
In cardiac hypertrophy, dysferlin enables tubular membrane proliferation, expanding the ER tubular network. This proliferation supports increased protein synthesis and calcium handling demands in hypertrophic cardiomyocytes. Dysferlin thus links tubular ER membrane dynamics to cardiac disease.
ER-to-Golgi Protein Delivery via Tubular Network
In simple terms: Proteins travel from the ER to the Golgi through a web of tubes.
The tubular ER network extends toward the Golgi and serves as a conduit for protein delivery. An interwoven tubular network mediates ER-to-Golgi transport, facilitating the movement of cargo carriers. This highlights the functional integration of the tubular ER membrane with the secretory pathway.
Key Genes Involved in GO:0098826 endoplasmic reticulum tubular network membrane
The following genes encode proteins that localize to or shape the endoplasmic reticulum tubular network membrane (GO:0098826), as supported by published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| RTN1 | Reticulon family member; stabilizes membrane curvature | Shapes tubular ER; implicated in neurodegeneration |
| RTN2 | Reticulon family member; curvature stabilization | Mutations linked to spastic paraplegia |
| RTN3 | Reticulon family member; curvature stabilization | Regulates ER morphology; role in apoptosis |
| RTN4 | Reticulon family member (Nogo); curvature stabilization | Inhibits axon regeneration; ER shaping |
| DP1 (TFG) | DP1/Yop1p family; curvature stabilization | Essential for tubular ER formation |
| ATL1 | Atlastin-1 GTPase; ER membrane fusion | Mutations cause hereditary spastic paraplegia |
| ATL2 | Atlastin-2 GTPase; ER membrane fusion | Regulated by lunapark ubiquitination |
| ATL3 | Atlastin-3 GTPase; ER membrane fusion | Required for tubular ER network |
| LNPK | Lunapark; ubiquitinates atlastin-2 | Regulates tubular network formation |
| DYSF | Dysferlin; tubular membrane proliferation | Enables cardiac hypertrophy |
| REEP5 | Receptor expression-enhancing protein; ER shaping | Interacts with reticulons |
| REEP1 | ER shaping protein | Mutations cause spastic paraplegia |
| REEP2 | ER shaping protein | Involved in tubular ER formation |
| REEP3 | ER shaping protein | Regulates ER morphology |
| REEP4 | ER shaping protein | Contributes to tubular ER network |
| REEP6 | ER shaping protein | Retinal degeneration linked |
| SEIPIN | ER membrane protein; lipid droplet formation | Interacts with tubular ER |
| CLIMP-63 | ER sheet protein; not tubular | Distinguishes sheet vs tubule domains |
How Is endoplasmic reticulum tubular network membrane Regulated?
The endoplasmic reticulum tubular network membrane is dynamically regulated by multiple mechanisms. Atlastin GTPases are regulated by GTP binding and hydrolysis, and their activity is modulated by lunapark-mediated ubiquitination. Reticulon and DP1/Yop1p protein levels influence the balance between tubular and sheet ER. Additionally, dysferlin-mediated tubular membrane proliferation is induced during cardiac hypertrophy, suggesting regulation by stress-responsive signaling pathways. The tubular network also responds to cellular demands for protein secretion, with ER-to-Golgi transport pathways influencing its extension and remodeling.
endoplasmic reticulum tubular network membrane and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ATL1 | Hereditary spastic paraplegia | Knockout or point-mutation in neurons |
| REEP1 | Hereditary spastic paraplegia | Knockout in motor neurons |
| DYSF | Cardiac hypertrophy | Overexpression in cardiomyocytes |
| LNPK | ER morphology defects | Knockout in HeLa cells |
| RTN2 | Spastic paraplegia | Knockout in mouse models |
Hereditary Spastic Paraplegia
Mutations in ATL1 (atlastin-1) and REEP1, which encode proteins essential for tubular ER membrane fusion and shaping, cause hereditary spastic paraplegia. These mutations impair tubular network formation, leading to axonal degeneration. This highlights the critical role of GO:0098826 in neuronal health.
Cardiac Hypertrophy
Dysferlin enables tubular membrane proliferation in cardiac hypertrophy, expanding the ER tubular network to meet increased synthetic demands. Dysferlin dysfunction may contribute to cardiomyopathy. Thus, GO:0098826 is linked to cardiac remodeling.
Platelet Disorders
Platelet production and ultrastructure depend on tubular ER membrane dynamics. Abnormalities in tubular ER proteins may affect platelet formation and function. This connects GO:0098826 to hematological disorders.
From endoplasmic reticulum tubular network membrane-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of ATL1 disrupt tubular ER network? | ATL1 knockout cell line |
| How does lunapark regulate atlastin-2? | LNPK knockout with rescue |
| Does dysferlin overexpression induce tubular proliferation? | DYSF overexpression in cardiomyocytes |
| Can reticulons alone generate tubules? | In vitro reconstitution with purified proteins |
| What is the role of REEP proteins in ER shaping? | REEP knockout or knockdown |
| How does ER-to-Golgi transport depend on tubular network? | Live-cell imaging with tagged cargo |
How to Study the endoplasmic reticulum tubular network membrane Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Live-cell imaging | Tubular ER dynamics and morphology | Real-time network remodeling |
| In vitro reconstitution | Minimal components for tubule formation | Mechanistic studies |
| Electron microscopy | Membrane ultrastructure and curvature | High-resolution imaging |
| Proteomics | Protein composition of tubular ER | Identifying novel components |
| FRAP | Protein mobility in tubular ER | Dynamic exchange |
| GTPase assays | Atlastin activity | Fusion mechanism |
| Ubiquitination assays | Lunapark-mediated ubiquitination | Regulation of atlastin-2 |
Live-Cell Fluorescence Imaging
Live-cell imaging with fluorescently tagged ER markers (e.g., Sec61β-GFP) allows visualization of tubular network dynamics. This method reveals real-time changes in tubular ER morphology and connectivity.
In Vitro Reconstitution
Reconstitution of tubular ER networks with purified components (reticulons, atlastin, lunapark) provides mechanistic insights into membrane shaping and fusion. This reductionist approach identifies minimal requirements for network formation.
Electron Microscopy
Electron microscopy, including focused ion beam scanning EM, resolves the ultrastructure of tubular ER membrane nanostructures. It provides high-resolution views of membrane curvature and protein localization.
Proteomics and Interactomics
Proteomic analysis of ER membrane fractions identifies proteins enriched in tubular versus sheet domains. Interaction studies reveal complexes involved in tubular network assembly.
How CRISPR Can Be Used to Study GO:0098826 endoplasmic reticulum tubular network membrane
Knockout
CRISPR knockout of genes encoding tubular ER proteins (e.g., ATL1, LNPK, RTN1) disrupts tubular network formation, enabling loss-of-function studies. These models reveal essential roles in ER morphology and cellular function.
Point Mutation
Point mutations in ATL1 or REEP1 associated with hereditary spastic paraplegia can be introduced via CRISPR to model disease-specific effects on tubular ER membrane dynamics.
Knock-in
Knock-in of fluorescent tags (e.g., GFP) into endogenous tubular ER genes allows real-time visualization of protein localization and dynamics in the tubular network.
Overexpression
CRISPR activation or cDNA overexpression of dysferlin or reticulons can induce tubular membrane proliferation, modeling cardiac hypertrophy or ER expansion.
How EDITGENE Supports endoplasmic reticulum tubular network membrane Research
Researchers studying endoplasmic reticulum tubular network membrane-related genes often need to determine whether a candidate gene is causally involved in tubular network formation, fusion, or disease. EDITGENE provides comprehensive CRISPR-based services to generate precisely engineered cell models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for endoplasmic reticulum tubular network membrane research.
Frequently Asked Questions About endoplasmic reticulum tubular network membrane
What is GO:0098826?
GO:0098826 is the Gene Ontology term for the endoplasmic reticulum tubular network membrane, the lipid bilayer surrounding the tubular portion of the ER.
What genes are involved in endoplasmic reticulum tubular network membrane?
Key genes include RTN1-4, DP1/TFG, ATL1-3, LNPK, DYSF, and REEP1-6, which encode proteins that shape, fuse, or regulate the tubular ER membrane.
What is the function of the ER tubular network membrane?
It provides a high-surface-area platform for lipid synthesis, calcium signaling, and ER-to-Golgi protein transport, and is essential for organelle connectivity.
How is the tubular ER network formed?
It is formed by membrane-shaping proteins like reticulons and DP1/Yop1p that stabilize curvature, and atlastin GTPases that fuse tubules, with regulation by lunapark.
What diseases are linked to tubular ER membrane proteins?
Mutations in ATL1 and REEP1 cause hereditary spastic paraplegia; dysferlin dysfunction is linked to cardiac hypertrophy; platelet disorders may involve tubular ER abnormalities.
What methods are used to study the ER tubular network membrane?
Live-cell imaging, in vitro reconstitution, electron microscopy, proteomics, and CRISPR-based genetic models are commonly used.
Can CRISPR be used to study tubular ER membrane genes?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models enable precise functional studies of tubular ER genes.
What is the role of atlastin in the tubular ER network?
Atlastin GTPases mediate homotypic fusion of ER tubules, a process essential for maintaining a continuous tubular network.
How does lunapark regulate the tubular ER network?
Lunapark ubiquitinates atlastin-2, modulating its activity to control tubular network formation.
What is the clinical relevance of the ER tubular network membrane?
It is implicated in hereditary spastic paraplegia, cardiac hypertrophy, and platelet disorders, making it a target for therapeutic research.
Conclusion
The endoplasmic reticulum tubular network membrane (GO:0098826) is a dynamic and essential membrane domain that underpins ER morphology, protein trafficking, and cellular homeostasis. Its assembly relies on conserved membrane-shaping proteins and fusion GTPases, and its dysfunction is linked to neurological and cardiac diseases. Continued research using advanced imaging, reconstitution, and CRISPR-based models will further elucidate its roles and therapeutic potential. EDITGENE offers comprehensive services to support these investigations.
References
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- 3. Thon JN et al.. 2012. Platelets: production, morphology and ultrastructure.. Handb Exp Pharmacol PMID: 22918725
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- 6. Paulke NJ et al.. 2024. Dysferlin Enables Tubular Membrane Proliferation in Cardiac Hypertrophy.. Circ Res 135(5):554-574 PMID: 39011635
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