GO:0043532 angiostatin binding: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0043532 angiostatin binding is a molecular function defined as binding to angiostatin, a proteolytic product of plasminogen or plasmin that contains at least one intact kringle domain and inhibits angiogenesis.
• Angiostatin is generated by proteolytic cleavage of plasminogen and retains kringle domains that mediate binding to endothelial cell surface proteins.
• Identified angiostatin-binding proteins include annexin II, angiomotin, actin, and ectopic ATP synthase, each contributing to anti-angiogenic and anti-migratory effects.
• Angiostatin binding can block matrix-enhanced plasminogen activation and inhibit endothelial and melanoma cellular invasion.
• The interaction between angiostatin and its binding partners regulates endothelial cell migration, tube formation, and angiogenesis.
• Experimental models for studying angiostatin binding include knockout, point-mutation, knock-in, and overexpression cell lines, as well as CRISPR library screening and bioinformatics analysis.
Description
Angiostatin binding (GO:0043532) is a molecular function that describes the selective interaction of a protein or cellular component with angiostatin, a proteolytic fragment of plasminogen or plasmin that contains at least one intact kringle domain and acts as an inhibitor of angiogenesis. This function is central to understanding how angiostatin exerts its anti-angiogenic effects at the cell surface and in the extracellular environment. The term is used in gene ontology annotations to capture the binding event itself, independent of downstream signaling or biological outcome. Researchers study angiostatin binding because it provides a mechanistic entry point into the regulation of angiogenesis, tumor invasion, and vascular remodeling. Several distinct angiostatin-binding proteins have been identified, including annexin II, angiomotin, actin, and ectopic ATP synthase, each with different structural features and cellular localizations. These interactions can modulate endothelial cell migration, tube formation, and matrix-enhanced plasminogen activation, making angiostatin binding a focal point for both basic vascular biology and translational cancer research. In practice, angiostatin binding is investigated using biochemical binding assays, cell-based migration and tube formation assays, and genetic perturbation of candidate binding partners. The availability of CRISPR-based knockout, point-mutation, knock-in, and overexpression models now allows researchers to test causality and dissect domain requirements for angiostatin binding in a controlled manner.
angiostatin binding At A Glance
| GO ID | GO:0043532 |
|---|---|
| GO term | angiostatin binding |
| Ontology | molecular_function |
| Synonym | none |
| Definition | Binding to angiostatin, a proteolytic product of plasminogen or plasmin containing at least one intact kringle domain, and which is an inhibitor of angiogenesis. |
| Major function | Mediates physical interaction with angiostatin, a kringle-domain-containing anti-angiogenic fragment of plasminogen/plasmin. |
| Representative binding partners | Annexin II, angiomotin, actin, and ectopic ATP synthase have been reported to bind angiostatin. |
| Associated processes | Regulation of endothelial cell migration, tube formation, and matrix-enhanced plasminogen activation. |
| Disease relevance | Angiogenesis, tumor invasion, and vascular biology. |
What Is GO:0043532?
In our own words, GO:0043532 angiostatin binding is the molecular function of physically interacting with angiostatin, a proteolytic product of plasminogen or plasmin that contains at least one intact kringle domain and functions as an angiogenesis inhibitor. The definition emphasizes the binding event to angiostatin itself, rather than to plasminogen or other kringle-containing fragments, and is therefore used to annotate proteins that directly recognize angiostatin.
Why Is angiostatin binding Important in Cell Biology?
Angiostatin binding is important because it defines the first molecular step through which angiostatin communicates with endothelial and tumor cells to suppress angiogenesis and invasion. Identifying and characterizing angiostatin-binding proteins helps explain how a single plasminogen fragment can produce pleiotropic anti-angiogenic effects, and it provides candidate targets for modulating angiogenesis in cancer and other vascular diseases.
• Defines the molecular recognition event for angiostatin, a key endogenous angiogenesis inhibitor.
• Links plasminogen proteolysis to endothelial cell surface binding and signaling.
• Involves multiple distinct binding partners, including annexin II, angiomotin, actin, and ectopic ATP synthase.
• Regulates endothelial cell migration and tube formation, core processes in angiogenesis.
• Can block matrix-enhanced plasminogen activation, affecting pericellular proteolysis.
• Relevant to tumor invasion and metastasis because angiostatin inhibits endothelial and melanoma cellular invasion.
• Provides a functional readout for testing candidate anti-angiogenic therapeutics.
• Supports CRISPR-based causal studies of candidate binding proteins.
• Helps interpret gene ontology annotations in vascular and cancer transcriptomics.
• Connects extracellular proteolysis, cell surface receptors, and cytoskeletal regulation.
Molecular Mechanism of angiostatin binding
Angiostatin generation and kringle domain recognition
In simple terms: Angiostatin is a piece of plasminogen that keeps at least one kringle domain, and binding proteins recognize this fragment.
Angiostatin is a proteolytic product of plasminogen or plasmin that contains at least one intact kringle domain and acts as an inhibitor of angiogenesis. The kringle domains are structurally conserved modules that mediate protein-protein interactions, and their presence is required for angiostatin to be recognized by its binding partners. This definitional feature distinguishes angiostatin binding from binding to full-length plasminogen or to other kringle-containing fragments.
Binding to annexin II through the lysine-binding domain
In simple terms: Angiostatin uses a lysine-binding region to attach to annexin II on endothelial cells.
Angiostatin binds to the tyrosine kinase substrate annexin II on endothelial cells through the lysine-binding domain. This interaction is one of the best-characterized angiostatin-binding events and provides a direct link between angiostatin and endothelial cell surface proteins that participate in signal transduction and membrane organization.
Interaction with angiomotin and regulation of migration
In simple terms: Angiomotin is an angiostatin-binding protein that controls how endothelial cells move and form tubes.
Angiomotin was identified as an angiostatin-binding protein that regulates endothelial cell migration and tube formation. The angiomotin family has been reviewed in detail, and its ability to bind angiostatin places it at the interface between anti-angiogenic signals and cytoskeletal regulation. This binding event is therefore directly relevant to the cellular behaviors that define angiogenesis.
Shared binding to actin and ectopic ATP synthase
In simple terms: Angiostatin can also stick to actin and to ATP synthase that appears on the cell surface.
Angiostatin and plasminogen share binding to endothelial cell surface actin, indicating that actin can serve as a common docking site for kringle-containing proteins. In addition, angiostatin binds ATP synthase on the surface of human endothelial cells, revealing an unexpected cell surface partner for this anti-angiogenic fragment. These interactions expand the repertoire of angiostatin-binding proteins beyond canonical receptors.
Functional consequences for plasminogen activation and invasion
In simple terms: When angiostatin binds its partners, it can shut down matrix-enhanced plasminogen activation and reduce cell invasion.
Angiostatin inhibits endothelial and melanoma cellular invasion by blocking matrix-enhanced plasminogen activation. This functional outcome is downstream of angiostatin binding to cell surface and matrix-associated proteins, and it illustrates how the binding event translates into reduced pericellular proteolysis and invasion. The molecular mechanism of angiostatin has been reviewed in the context of specificity and regulation, emphasizing that binding interactions are central to its activity.
Key Genes Involved in GO:0043532 angiostatin binding
The following genes and proteins have been directly implicated in angiostatin binding or in the functional consequences of this molecular function.
| Gene | Major Role | Research Relevance |
|---|---|---|
| ANXA2 | Annexin II binds angiostatin through its lysine-binding domain on endothelial cells. | Cell surface binding partner; target for knockout and point-mutation studies of the lysine-binding domain. |
| AMOT | Angiomotin binds angiostatin and regulates endothelial cell migration and tube formation. | Central angiostatin-binding protein for migration and tube formation assays. |
| AMOTL1 | Angiomotin-like protein 1 is a member of the angiomotin family reviewed in the context of angiostatin binding. | Candidate paralog for comparative knockout and knock-in studies. |
| AMOTL2 | Angiomotin-like protein 2 is a member of the angiomotin family reviewed in the context of angiostatin binding. | Candidate paralog for functional redundancy studies. |
| PLG | Plasminogen is the precursor of angiostatin; proteolysis generates the kringle-containing fragment. | Source protein for angiostatin generation; relevant to overexpression and processing studies. |
| PLAT | Tissue-type plasminogen activator contributes to plasminogen activation and angiostatin generation. | Upstream regulator of angiostatin production; candidate for perturbation studies. |
| PLAU | Urokinase-type plasminogen activator contributes to plasminogen activation and angiostatin generation. | Upstream regulator of angiostatin production; candidate for perturbation studies. |
| ACTB | Beta-actin is part of the endothelial cell surface actin that binds angiostatin and plasminogen. | Shared binding partner for angiostatin and plasminogen. |
| ACTG1 | Gamma-actin is a cytoskeletal actin isoform relevant to cell surface actin pools. | Candidate for actin isoform-specific binding studies. |
| ATP5F1A | ATP synthase subunit alpha is part of the ectopic ATP synthase complex that binds angiostatin on endothelial cells. | Cell surface ATP synthase binding partner. |
| ATP5F1B | ATP synthase subunit beta is part of the ectopic ATP synthase complex that binds angiostatin. | Cell surface ATP synthase binding partner. |
| KDR | VEGFR2 is a key endothelial receptor tyrosine kinase in angiogenesis, providing context for angiostatin binding effects. | Pathway context for angiostatin binding studies. |
| TEK | TIE2 is an endothelial receptor tyrosine kinase involved in vascular stabilization, relevant to angiostatin biology. | Pathway context for angiostatin binding studies. |
| MMP2 | Matrix metalloproteinase 2 contributes to extracellular matrix remodeling and can influence angiostatin generation. | Candidate modifier of angiostatin availability. |
| MMP9 | Matrix metalloproteinase 9 contributes to extracellular matrix remodeling and can influence angiostatin generation. | Candidate modifier of angiostatin availability. |
| SERPINE1 | PAI-1 regulates plasminogen activation and thereby affects angiostatin generation. | Regulatory node for angiostatin production. |
| PLG2 | Plasminogen-related locus component relevant to kringle domain biology. | Comparative kringle domain studies. |
| ANXA2R | Annexin II receptor-like context for annexin II-mediated angiostatin binding. | Candidate for cell surface binding complex studies. |
How Is angiostatin binding Regulated?
Angiostatin binding is regulated at multiple levels. The availability of angiostatin itself depends on plasminogen activation and proteolytic processing, which are controlled by plasminogen activators and their inhibitors. At the cell surface, the presence and accessibility of binding partners such as annexin II, angiomotin, actin, and ectopic ATP synthase determine whether angiostatin can engage its targets. The molecular mechanism of angiostatin has been reviewed with emphasis on specificity and regulation, indicating that binding is not a constitutive event but is modulated by the cellular context and the extracellular proteolytic environment.
angiostatin binding and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ANXA2 | Tumor angiogenesis and endothelial cell surface binding | ANXA2 knockout endothelial cells for angiostatin binding assays |
| AMOT | Endothelial migration and tube formation in angiogenesis | AMOT knockout and rescue models for tube formation |
| PLG | Plasminogen proteolysis and angiostatin generation | PLG overexpression and processing models |
| ACTB | Cell surface actin binding and cytoskeletal regulation | ACTB point-mutation models for actin-binding studies |
| ATP5F1A | Ectopic ATP synthase binding on endothelial cells | ATP5F1A knockout and cell surface labeling models |
Angiostatin binding in cancer and tumor angiogenesis
Angiostatin binding is directly relevant to cancer because angiostatin inhibits endothelial and melanoma cellular invasion by blocking matrix-enhanced plasminogen activation. Tumor angiogenesis depends on endothelial cell migration and tube formation, processes that are suppressed when angiostatin engages binding partners such as angiomotin. Therefore, proteins that mediate angiostatin binding are candidate targets for anti-angiogenic strategies in oncology.
Angiostatin binding and vascular remodeling
Beyond cancer, angiostatin binding influences vascular remodeling by modulating endothelial cell migration and tube formation. The interaction with cell surface actin and ectopic ATP synthase suggests that angiostatin can affect endothelial cell surface events that are important for vascular homeostasis. Dysregulation of these binding events may contribute to pathological angiogenesis in ischemic and inflammatory conditions.
Angiostatin binding and extracellular proteolysis
Because angiostatin is a proteolytic fragment of plasminogen, its binding is intimately linked to the plasminogen activation system. Angiostatin binding can block matrix-enhanced plasminogen activation, thereby reducing pericellular proteolysis and invasion. This places angiostatin binding at the intersection of extracellular matrix remodeling and cell invasion, with implications for diseases characterized by excessive proteolysis.
From angiostatin binding-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of a candidate gene reduce angiostatin binding? | CRISPR knockout cell line followed by biochemical binding assay |
| Which domain of annexin II is required for angiostatin binding? | Point-mutation knock-in of the lysine-binding domain |
| Can a tagged binding partner be used to purify angiostatin complexes? | Tagged knock-in of the endogenous locus |
| Does overexpression of angiomotin enhance angiostatin-mediated effects? | Overexpression cell model with migration and tube formation assays |
| Which genes modulate angiostatin binding at genome scale? | CRISPR library screening with binding readout |
| How does angiostatin binding affect plasminogen activation? | Knockout and overexpression models combined with plasminogen activation assays |
How to Study the angiostatin binding Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Solid-phase binding assay | Direct binding of angiostatin to immobilized proteins | Validate candidate binding partners such as annexin II |
| Co-immunoprecipitation | Physical interaction between angiostatin and proteins in cell lysates | Confirm actin and angiomotin binding |
| Surface plasmon resonance | Kinetics and affinity of angiostatin binding | Compare binding of kringle-containing fragments |
| Endothelial migration assay | Cell migration in response to angiostatin | Test angiomotin-dependent effects |
| Tube formation assay | In vitro angiogenesis capacity | Assess angiostatin binding on tube formation |
| Plasminogen activation assay | Matrix-enhanced plasminogen activation | Measure functional inhibition by angiostatin |
| Invasion assay | Cellular invasion through matrix | Evaluate endothelial and melanoma invasion |
| Affinity proteomics | Identification of novel angiostatin-binding proteins | Discover cell surface binding partners |
Biochemical binding assays
Direct binding of angiostatin to candidate proteins can be measured using solid-phase binding assays, surface plasmon resonance, or co-immunoprecipitation. These approaches have been used to demonstrate binding of angiostatin to annexin II, actin, and ectopic ATP synthase. They provide quantitative readouts of affinity and specificity for angiostatin versus related kringle-containing fragments.
Cell migration and tube formation assays
Functional consequences of angiostatin binding are commonly assessed using endothelial cell migration and tube formation assays. Angiomotin was identified as an angiostatin-binding protein that regulates these processes, making such assays a standard readout for angiostatin biology. Combining these assays with genetic perturbation allows causal testing of binding partners.
Plasminogen activation and invasion assays
Because angiostatin inhibits matrix-enhanced plasminogen activation, assays that measure plasminogen activation and cellular invasion are useful for studying downstream effects of angiostatin binding. These assays can be performed in endothelial and melanoma cell models to link binding events to invasive behavior.
Proteomics and interactomics
Proteomic approaches such as affinity purification coupled to mass spectrometry can identify novel angiostatin-binding proteins. This strategy is supported by the diversity of known binding partners, including annexin II, angiomotin, actin, and ATP synthase. Interactomics can also reveal context-dependent binding complexes.
How CRISPR Can Be Used to Study GO:0043532 angiostatin binding
Knockout
CRISPR knockout of candidate angiostatin-binding genes such as ANXA2 or AMOT can be used to test whether loss of the protein reduces angiostatin binding and downstream anti-angiogenic effects. Knockout endothelial cell lines are particularly useful for migration and tube formation assays.
Point Mutation
Point mutations can be introduced into domains required for angiostatin binding, such as the lysine-binding domain of annexin II. Such models allow precise structure-function analysis without eliminating the entire protein.
Knock-in
Knock-in of epitope tags or fluorescent reporters at endogenous loci enables visualization and purification of angiostatin-binding complexes. Tagged knock-in models are valuable for interactomics and imaging studies.
Overexpression
Overexpression of angiostatin-binding proteins such as angiomotin can enhance angiostatin-mediated effects on endothelial cell migration and tube formation. Overexpression models are useful for gain-of-function studies and for testing dose-dependent responses.
How EDITGENE Supports angiostatin binding Research
Researchers studying angiostatin binding-related genes often need to determine whether a candidate gene is causally involved in binding, downstream signaling, or functional outcomes such as migration and tube formation. EDITGENE provides CRISPR-based cell model services that enable precise genetic perturbation of these candidates in relevant endothelial and tumor cell backgrounds.
Contact EDITGENE today to design your custom CRISPR model for angiostatin binding research.
Frequently Asked Questions About angiostatin binding
What is angiostatin binding?
Angiostatin binding (GO:0043532) is the molecular function of binding to angiostatin, a proteolytic product of plasminogen or plasmin that contains at least one intact kringle domain and inhibits angiogenesis.
What genes are involved in angiostatin binding?
Genes encoding reported angiostatin-binding proteins include ANXA2 (annexin II), AMOT (angiomotin), ACTB (actin), and ATP5F1A/ATP5F1B (ectopic ATP synthase subunits).
What is the GO ID for angiostatin binding?
The Gene Ontology ID for angiostatin binding is GO:0043532, and it belongs to the molecular_function ontology.
How does angiostatin bind to endothelial cells?
Angiostatin binds to endothelial cell surface proteins such as annexin II through its lysine-binding domain, and it also binds actin and ectopic ATP synthase.
What is angiomotin and how does it relate to angiostatin?
Angiomotin is an angiostatin-binding protein that regulates endothelial cell migration and tube formation, making it a key mediator of angiostatin function.
Does angiostatin binding affect plasminogen activation?
Yes, angiostatin inhibits endothelial and melanoma cellular invasion by blocking matrix-enhanced plasminogen activation.
What diseases are associated with angiostatin binding?
Angiostatin binding is relevant to cancer and tumor angiogenesis, as well as vascular remodeling and diseases involving excessive extracellular proteolysis.
How can I study angiostatin binding in the lab?
Common methods include biochemical binding assays, co-immunoprecipitation, endothelial migration and tube formation assays, plasminogen activation assays, and affinity proteomics.
Can CRISPR be used to study angiostatin binding?
Yes, CRISPR knockout, point-mutation, knock-in, and overexpression models allow causal testing of candidate angiostatin-binding genes and their domains.
What cell models are suitable for angiostatin binding research?
Endothelial cell models are widely used because angiostatin acts on endothelial cells, and melanoma cell models are also relevant for invasion studies.
Conclusion
GO:0043532 angiostatin binding captures a specific molecular function that connects the proteolytic fragment angiostatin to cell surface and extracellular binding partners such as annexin II, angiomotin, actin, and ectopic ATP synthase. This binding event underlies the anti-angiogenic and anti-invasive effects of angiostatin, including inhibition of matrix-enhanced plasminogen activation and regulation of endothelial migration and tube formation. For researchers, angiostatin binding offers a tractable entry point into angiogenesis biology and cancer research. CRISPR-based knockout, point-mutation, knock-in, and overexpression models, combined with biochemical and functional assays, enable rigorous dissection of which proteins bind angiostatin and how those interactions shape vascular and tumor phenotypes.
References
- 1. Tuszynski GP et al.. 2002. Angiostatin binds to tyrosine kinase substrate annexin II through the lysine-binding domain in endothelial cells.. Microvasc Res 64(3):448-62 PMID: 12453439
- 3. Wahl ML et al.. 2005. Angiostatin's molecular mechanism: aspects of specificity and regulation elucidated.. J Cell Biochem 96(2):242-61 PMID: 16094651
- 4. Dudani AK et al.. 2005. Angiostatin and plasminogen share binding to endothelial cell surface actin.. Biochem Cell Biol 83(1):28-35 PMID: 15746964
- 5. Stack MS et al.. 1999. Angiostatin inhibits endothelial and melanoma cellular invasion by blocking matrix-enhanced plasminogen activation.. Biochem J 340 ( Pt 1)(Pt 1):77-84 PMID: 10229661
- 6. Moleirinho S et al.. 2014. The Angiomotins--from discovery to function.. FEBS Lett 588(16):2693-703 PMID: 24548561
- 7. Troyanovsky B et al.. 2001. Angiomotin: an angiostatin binding protein that regulates endothelial cell migration and tube formation.. J Cell Biol 152(6):1247-54 PMID: 11257124
- 8. Moser TL et al.. 1999. Angiostatin binds ATP synthase on the surface of human endothelial cells.. Proc Natl Acad Sci U S A 96(6):2811-6 PMID: 10077593
