GO:0035371 microtubule plus-end: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0035371 (microtubule plus-end) is the growing end of a microtubule where polymerization is fastest and dynamic instability occurs.
• Plus-end tracking proteins (+TIPs) such as EB1, CLIP-170, and APC accumulate at this site and regulate microtubule dynamics.
• Phase separation of EB1 and other +TIPs organizes plus-end dynamics, particularly during mitosis.
• The plus-end is a signaling hub that coordinates cell polarity, migration, and neuronal development.
• Dysregulation of plus-end proteins is linked to cancer, neurodegeneration, and developmental disorders.
• CRISPR knockout, knock-in, and overexpression models are essential for dissecting plus-end protein function.
Description
The microtubule plus-end (GO:0035371) is the growing end of a microtubule, where tubulin dimers add more rapidly than at the minus end. In cells, this end undergoes dynamic instability, switching between growth and shortening phases, and serves as a platform for a diverse group of proteins known as plus-end tracking proteins (+TIPs). These proteins accumulate at the plus-end and regulate microtubule dynamics, interactions with cellular structures, and signaling events. Understanding the plus-end is critical because it governs fundamental processes such as mitotic spindle positioning, cell migration, and neuronal morphogenesis. This article synthesizes authoritative QuickGO data and verified PubMed literature to provide a research-grade overview of the microtubule plus-end, its components, mechanisms, and methods for study.
microtubule plus-end At A Glance
| GO ID | GO:0035371 |
|---|---|
| GO term | microtubule plus-end |
| Ontology | cellular_component |
| Synonym | growing microtubule plus end; microtubule plus end |
| Major function | Site of rapid microtubule polymerization and dynamic instability; hub for +TIP proteins |
| Key proteins | EB1, CLIP-170, APC, CLASPs, XMAP215, dynein/dynactin |
| Cellular processes | Mitosis, cell migration, neuronal development, intracellular transport |
| Research methods | Live-cell imaging, TIRF microscopy, CRISPR KO/KI, proteomics |
What Is GO:0035371?
The microtubule plus-end is defined by GO:0035371 as the growing (plus) end of a microtubule. In vitro, microtubules polymerize more quickly at the plus end than at the minus end. In vivo, microtubule growth occurs only at the plus end, and the plus end switches between periods of growth and shortening, a behavior known as dynamic instability.
Why Is microtubule plus-end Important in Cell Biology?
The microtubule plus-end is a central regulator of cytoskeletal dynamics and cellular organization. It controls where and when microtubules grow, thereby influencing cell shape, polarity, and division. Plus-end tracking proteins mediate interactions between microtubules and other cellular components, including kinetochores, cell cortex, and organelles. Defects in plus-end regulation are associated with cancer progression, neurodevelopmental disorders, and neurodegeneration. Thus, studying the plus-end provides insights into basic cell biology and disease mechanisms.
• Regulates dynamic instability, essential for microtubule function.
• Coordinates mitotic spindle assembly and chromosome segregation.
• Controls cell polarity and directed migration.
• Essential for neuronal development and axon guidance.
• Involved in intracellular transport and organelle positioning.
• Dysregulation linked to cancer cell invasion and metastasis.
• Implicated in neurodegenerative diseases such as Alzheimer's.
• Target for chemotherapeutic agents that disrupt microtubules.
• Provides a model for studying protein phase separation.
• Enables high-resolution imaging of cytoskeletal dynamics.
What Happens During microtubule plus-end?
Microtubule polymerization and dynamic instability
In simple terms: Microtubules grow by adding tubulin at their plus end, but they can suddenly shrink, a behavior called dynamic instability.
At the plus-end, GTP-bound tubulin dimers add preferentially, leading to rapid growth. Hydrolysis of GTP to GDP in the lattice destabilizes the microtubule, causing catastrophe and shrinkage. This switch between growth and shortening is known as dynamic instability and is fundamental to microtubule function.
Plus-end tracking protein (+TIP) accumulation
In simple terms: Special proteins ride the growing plus-end and control its behavior.
+TIPs such as EB1, CLIP-170, and APC recognize the plus-end structure and accumulate there. They form a dynamic network that regulates microtubule dynamics and connects microtubules to cellular targets. EB1, for example, binds to the plus-end and recruits other proteins, influencing catastrophe frequency.
Phase separation at the plus-end
In simple terms: Some plus-end proteins can form liquid-like droplets that organize the microtubule tip.
Recent studies show that EB1 and other +TIPs undergo phase separation, forming condensates that concentrate regulatory factors at the plus-end. This phase separation guides microtubule dynamics, especially during mitosis.
Interactions with cellular structures
In simple terms: The plus-end connects microtubules to other parts of the cell, like the cortex or kinetochores.
Plus-end proteins mediate interactions between microtubules and the cell cortex, kinetochores, and organelles. For example, dynein/dynactin is targeted to the plus-end and generates forces for spindle positioning and nuclear migration.
Key Genes Involved in GO:0035371 microtubule plus-end
The following genes encode key proteins that localize to or regulate the microtubule plus-end.
| Gene | Major Role | Research Relevance |
|---|---|---|
| MAPRE1 (EB1) | Core +TIP, regulates microtubule dynamics and phase separation | Knockout causes mitotic defects; phase separation studies |
| CLIP1 (CLIP-170) | Links microtubules to endosomes and kinetochores | Knockout affects cell migration and polarity |
| APC | Tumor suppressor, regulates microtubule stability | Mutations in colorectal cancer; plus-end tracking |
| CLASP1/2 | Promotes microtubule rescue and stabilization | Knockout leads to spindle defects |
| CKAP5 (XMAP215) | Processive polymerase, accelerates growth | Knockout reduces microtubule growth rate |
| DCTN1 (p150glued) | Dynein/dynactin subunit, targets plus-end | Knockout impairs nuclear migration |
| KIF11 (Eg5) | Kinesin motor, crosslinks microtubules | Inhibitors used in cancer therapy |
| STMN1 (Stathmin) | Sequesters tubulin, promotes catastrophe | Overexpression in cancer |
| TACC3 | Centrosomal and spindle protein | Knockout causes mitotic arrest |
| MAPRE2 | EB family member, regulates microtubule dynamics | Knockout affects neuronal development |
| MAPRE3 | EB family member, neuronal specific | Knockout impairs axon growth |
| DYNLL1 | Dynein light chain, interacts with +TIPs | Knockout affects transport |
| KIF2A | Kinesin-13, depolymerase | Knockout increases microtubule length |
| KIF2C (MCAK) | Kinesin-13, depolymerase at plus-end | Knockout causes mitotic defects |
| SPAST | Microtubule severing protein | Mutations in hereditary spastic paraplegia |
| MAPT (Tau) | Microtubule stabilizer | Mutations in frontotemporal dementia |
| TUBB | Beta-tubulin subunit | Mutations cause tubulinopathies |
| TUBG1 | Gamma-tubulin, nucleation | Mutations cause cortical dysplasia |
How Is microtubule plus-end Regulated?
The microtubule plus-end is regulated by phosphorylation of +TIPs, such as EB1 and CLIP-170, which modulates their binding to microtubules. Phase separation of EB1 is regulated by its concentration and post-translational modifications. Additionally, mitotic kinases such as CDK1 and Aurora A control plus-end dynamics during cell division.
microtubule plus-end and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| APC | Colorectal cancer | Knockout in HCT116 cells |
| MAPT | Frontotemporal dementia | Knock-in of mutant Tau in iPSCs |
| SPAST | Hereditary spastic paraplegia | Knockout in motor neurons |
| TUBB | Tubulinopathy | Point mutation knock-in in HEK293 |
| MAPRE1 | Cancer progression | Overexpression in HeLa cells |
Cancer
Dysregulation of plus-end proteins contributes to cancer. APC mutations are common in colorectal cancer and affect microtubule plus-end tracking. Overexpression of EB1 and stathmin promotes cell migration and invasion. Targeting plus-end dynamics is a strategy in chemotherapy.
Neurodegeneration
Neurons rely on plus-end dynamics for axon growth and guidance. Mutations in MAPT (Tau) and SPAST impair microtubule regulation, leading to frontotemporal dementia and hereditary spastic paraplegia, respectively. Plus-end proteins are implicated in Alzheimer's disease.
Developmental disorders
Mutations in tubulin genes (TUBB, TUBG1) cause tubulinopathies, including cortical dysplasia and microcephaly, due to defective microtubule dynamics. Plus-end proteins are essential for neuronal development.
From microtubule plus-end-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does EB1 phase separation regulate mitotic spindle? | Knockout + rescue with phase-separation mutants |
| How does APC mutation affect plus-end tracking? | Point mutation knock-in in colorectal cancer cells |
| What is the role of CLIP-170 in cell migration? | Knockout in fibroblasts |
| Does Tau mutation alter microtubule dynamics? | Knock-in of mutant Tau in neurons |
| Can overexpression of EB1 drive invasion? | Overexpression in breast cancer cells |
| What is the interactome of plus-end proteins? | Tagged knock-in (GFP) + proteomics |
How to Study the microtubule plus-end Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Live-cell imaging | Plus-end tracking, dynamic instability | EB1-GFP in HeLa cells |
| TIRF microscopy | In vitro microtubule growth and +TIP binding | Reconstitution with purified proteins |
| CRISPR knockout screen | Genes affecting plus-end dynamics | Genome-wide screen in cancer cells |
| AP-MS | Protein-protein interactions | EB1 interactome |
| Proximity ligation assay | In situ interactions at plus-end | CLIP-170 and dynein |
| FRAP | Turnover of +TIPs at plus-end | EB1 dynamics |
| RNA-seq | Transcriptional changes upon knockout | Plus-end gene KO |
| Phosphoproteomics | Phosphorylation of +TIPs | Mitotic regulation |
Live-cell imaging of plus-end dynamics
Fluorescently labeled +TIPs (e.g., EB1-GFP) allow tracking of microtubule plus-ends in living cells. This reveals growth rates, catastrophe frequencies, and phase separation.
TIRF microscopy for in vitro reconstitution
Total internal reflection fluorescence (TIRF) microscopy visualizes individual microtubules and plus-end protein binding in vitro, providing mechanistic insights.
CRISPR screening for plus-end regulators
Genome-wide CRISPR knockout screens identify genes that affect microtubule dynamics or plus-end protein localization.
Proteomics of plus-end complexes
Affinity purification coupled with mass spectrometry (AP-MS) of plus-end proteins reveals interaction networks and regulatory partners.
How CRISPR Can Be Used to Study GO:0035371 microtubule plus-end
Knockout
CRISPR knockout of plus-end genes (e.g., MAPRE1, CLIP1) reveals their essential roles in microtubule dynamics, mitosis, and migration. Knockout cell lines are valuable for studying loss-of-function phenotypes.
Point Mutation
Introducing point mutations (e.g., in APC or TUBB) via CRISPR allows modeling of disease-associated variants and dissecting domain functions.
Knock-in
Knock-in of fluorescent tags (e.g., GFP-EB1) enables real-time imaging of plus-end dynamics at endogenous expression levels.
Overexpression
Overexpression of plus-end proteins (e.g., EB1, stathmin) via CRISPR activation or lentiviral delivery models gain-of-function effects in cancer and neuronal development.
How EDITGENE Supports microtubule plus-end Research
Researchers studying microtubule plus-end-related genes often need to determine whether a candidate gene is causally involved in plus-end dynamics, and to dissect its molecular function using precise genome editing. EDITGENE provides a comprehensive suite of CRISPR services to accelerate this research.
Contact EDITGENE today to design your custom CRISPR model for microtubule plus-end research.
Frequently Asked Questions About microtubule plus-end
What is the microtubule plus-end?
The microtubule plus-end (GO:0035371) is the growing end of a microtubule where polymerization is fastest and dynamic instability occurs.
What genes are involved in microtubule plus-end?
Key genes include MAPRE1 (EB1), CLIP1, APC, CLASP1/2, CKAP5, and DCTN1.
What are plus-end tracking proteins?
Plus-end tracking proteins (+TIPs) are a group of proteins that accumulate at the microtubule plus-end and regulate its dynamics.
How does EB1 regulate microtubule plus-end?
EB1 binds to the plus-end, recruits other proteins, and undergoes phase separation to organize microtubule dynamics.
What diseases are associated with microtubule plus-end dysfunction?
Cancer, neurodegeneration, and developmental disorders such as tubulinopathies.
How can I study microtubule plus-end in the lab?
Use live-cell imaging, TIRF microscopy, CRISPR knockout, and proteomics.
What is dynamic instability?
Dynamic instability is the switching of microtubule plus-ends between growth and shortening phases.
What is the role of phase separation at the plus-end?
Phase separation of EB1 and other +TIPs concentrates regulatory factors and guides microtubule dynamics, especially in mitosis.
Can CRISPR be used to study plus-end proteins?
Yes, CRISPR knockout, knock-in, and point mutation models are widely used to dissect plus-end protein functions.
What methods are used to analyze plus-end dynamics?
Live-cell imaging, TIRF, FRAP, and CRISPR screens are common methods.
Conclusion
The microtubule plus-end (GO:0035371) is a dynamic and essential cellular component that governs microtubule behavior and cellular organization. Its study has revealed fundamental mechanisms such as dynamic instability and phase separation, with direct implications for cancer, neurodegeneration, and development. Continued research using advanced CRISPR models and imaging techniques will further illuminate its roles and therapeutic potential.
References
- 1. Song X et al.. 2023. Phase separation of EB1 guides microtubule plus-end dynamics.. Nat Cell Biol 25(1):79-91 PMID: 36536176
- 2. Akhmanova A et al.. 2005. Microtubule plus-end-tracking proteins: mechanisms and functions.. Curr Opin Cell Biol 17(1):47-54 PMID: 15661518
- 3. van de Willige D et al.. 2016. Microtubule plus-end tracking proteins in neuronal development.. Cell Mol Life Sci 73(10):2053-77 PMID: 26969328
- 4. Jaworski J et al.. 2008. Microtubule plus-end tracking proteins in differentiated mammalian cells.. Int J Biochem Cell Biol 40(4):619-37 PMID: 18023603
- 5. Galjart N. 2010. Plus-end-tracking proteins and their interactions at microtubule ends.. Curr Biol 20(12):R528-37 PMID: 20620909
- 7. Lansbergen G et al.. 2006. Microtubule plus end: a hub of cellular activities.. Traffic 7(5):499-507 PMID: 16643273
- 8. Yang F et al.. 2024. Organization of microtubule plus-end dynamics by phase separation in mitosis.. J Mol Cell Biol 16(2) PMID: 38323478
