GO:0034713 type I transforming growth factor beta receptor binding: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0034713 describes the molecular function of binding to a type I transforming growth factor beta (TGF-beta) receptor, a critical step in TGF-beta signal transduction [2, 5].
• This binding event typically involves ligands such as TGF-beta isoforms or other proteins that directly interact with the type I receptor (e.g., TGFBR1) to initiate downstream signaling [3, 8].
• The type I receptor is a serine/threonine kinase that, upon binding, phosphorylates SMAD proteins to propagate signals to the nucleus [7, 8].
• Dysregulation of this binding function is implicated in cancer, fibrosis, and acute lung injury, making it a therapeutic target [4, 6].
• Research methods to study this term include kinase assays, co-immunoprecipitation, and CRISPR-based knockout of receptor or ligand genes [1, 6].
• EDITGENE offers CRISPR services to model this interaction, including knockout, point mutation, and knock-in cell lines for functional studies.
Description
The molecular function defined by GO:0034713, type I transforming growth factor beta receptor binding, refers to the selective interaction of a protein or ligand with a type I TGF-beta receptor. This binding event is a pivotal step in the TGF-beta signaling cascade, which regulates diverse cellular processes including proliferation, differentiation, and apoptosis [2, 5]. The type I receptor, a transmembrane serine/threonine kinase, is activated upon binding, leading to phosphorylation of downstream SMAD effectors. Understanding this binding function is essential for deciphering how TGF-beta signals are initiated and propagated. Researchers study this term to identify novel ligands, characterize receptor-ligand interfaces, and develop inhibitors for diseases where TGF-beta signaling is aberrant [1, 6]. The binding specificity and affinity are critical determinants of signaling outcomes, and mutations that alter this interaction can lead to pathological conditions [4, 7].
type I transforming growth factor beta receptor binding At A Glance
| GO ID | GO:0034713 |
|---|---|
| GO term | type I transforming growth factor beta receptor binding |
| Ontology | molecular_function |
| Synonym | TGF-beta type I binding; type I TGF-beta binding; babo binding; sax binding; tkv binding |
| Major function | Binding to a type I TGF-beta receptor, initiating or modulating TGF-beta signaling |
| Definition | Binding to a type I transforming growth factor beta receptor. |
| Related receptors | TGFBR1 (ALK5), ACVR1B (ALK4), ACVR1C (ALK7) |
| Related ligands | TGF-beta1, TGF-beta2, TGF-beta3, activins, inhibins |
What Is GO:0034713?
GO:0034713 is a molecular function term that describes the binding of a molecule to a type I transforming growth factor beta receptor. This binding is non-covalent and selective, typically involving a ligand or accessory protein that docks onto the extracellular or intracellular domain of the receptor. The term encompasses interactions that lead to receptor activation or modulation, as opposed to merely sequestering the receptor. It is a key event in TGF-beta signal transduction, where the type I receptor acts as a signal transducer upon binding [2, 5].
Why Is type I transforming growth factor beta receptor binding Important in Cell Biology?
GO:0034713 is important because it represents the initial molecular recognition event that triggers the canonical TGF-beta signaling pathway, which controls a vast array of biological processes. Dysregulation of this binding function is associated with cancer progression, fibrosis, and inflammatory diseases [4, 6]. For example, aberrant binding of TGF-beta to its type I receptor can promote tumor metastasis and epithelial-mesenchymal transition. Therefore, understanding the structural and biochemical basis of this binding is crucial for designing targeted therapies that block or enhance TGF-beta signaling [1, 7].
• Initiates TGF-beta signaling, a pathway central to cell growth, differentiation, and immune regulation [2, 8].
• Mutations in the type I receptor or its ligands that affect binding can cause diseases such as cancer and fibrosis [4, 6].
• The binding event is a target for small molecule inhibitors like SB505124, which block receptor kinase activity.
• It is essential for embryonic development and tissue homeostasis, as shown by knockout studies in model organisms.
• Binding specificity determines whether TGF-beta, activin, or other ligands activate distinct SMAD branches.
• Research on this term aids in understanding cross-talk with other pathways, such as PI3K/AKT, via direct receptor interactions.
• It provides a basis for engineering receptors or ligands with altered binding properties for therapeutic applications.
• Studying this binding helps explain how cells interpret graded TGF-beta signals into diverse transcriptional outputs.
Molecular Mechanism of type I transforming growth factor beta receptor binding
Ligand recognition and receptor complex assembly
In simple terms: A ligand binds to the type I receptor, often with help from a type II receptor, to form a signaling complex.
The binding of a ligand to a type I TGF-beta receptor typically begins with the ligand forming a complex with a type II receptor, which then recruits and phosphorylates the type I receptor. This assembly is essential for signal transduction [2, 8]. The type I receptor's extracellular domain provides the binding interface, while the intracellular kinase domain becomes activated upon complex formation.
Conformational changes and kinase activation
In simple terms: Once the ligand binds, the receptor changes shape and turns on its enzymatic activity.
Binding induces conformational changes in the type I receptor that relieve autoinhibition, allowing the kinase domain to phosphorylate downstream substrates. This activation is a key consequence of the binding event described by GO:0034713. The kinase activity is directed towards SMAD proteins, which then translocate to the nucleus.
Substrate specificity and SMAD phosphorylation
In simple terms: The activated receptor adds phosphate groups to SMAD proteins, which carry the signal to the nucleus.
The type I receptor kinase specifically phosphorylates receptor-regulated SMADs (R-SMADs) at their C-terminal SSXS motif. This phosphorylation is a direct outcome of the binding function and is required for most TGF-beta responses [7, 8]. The specificity of binding ensures that the correct R-SMADs are activated in response to particular ligands.
Regulation by accessory proteins and inhibitors
In simple terms: Other proteins can enhance or block the binding to fine-tune the signal.
Accessory proteins such as betaglycan can present ligands to the type I receptor, while inhibitory proteins like FKBP12 can prevent inappropriate activation. The binding function is thus regulated at multiple levels [5, 8]. Small molecule inhibitors like SB505124 compete with ATP binding to the kinase domain, indirectly affecting the consequences of receptor binding.
Key Genes Involved in GO:0034713 type I transforming growth factor beta receptor binding
The following genes encode proteins that participate in or regulate the binding to type I TGF-beta receptors, as supported by published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| TGFBR1 | Type I TGF-beta receptor; binds ligands and transduces signals | Central to GO:0034713; mutations linked to cancer and fibrosis [1, 8] |
| TGFBR2 | Type II TGF-beta receptor; presents ligands to type I receptor | Required for ligand-induced type I receptor binding and activation [4, 8] |
| TGFB1 | Ligand that binds to type I receptor complex | Key isoform in fibrosis and cancer; binding affinity studied [3, 8] |
| TGFB2 | Ligand that binds to type I receptor complex | Isoform with distinct binding properties; involved in development |
| TGFB3 | Ligand that binds to type I receptor complex | Isoform implicated in wound healing and cancer |
| ACVR1B | Type I receptor (ALK4) for activin; binds activin ligands | Mediates activin signaling; shares binding mechanisms |
| ACVR1C | Type I receptor (ALK7) for activin; binds activin ligands | Regulates metabolic and developmental processes |
| SMAD2 | Downstream effector phosphorylated by activated type I receptor | Readout of receptor binding and activation |
| SMAD3 | Downstream effector phosphorylated by activated type I receptor | Readout of receptor binding and activation |
| SMAD4 | Co-SMAD that complexes with R-SMADs | Required for transcriptional responses after receptor binding |
| FKBP12 | Inhibitory protein that binds type I receptor | Regulates receptor activation by preventing ligand-independent signaling |
| BETAGLYCAN | Accessory receptor that presents ligands to type II receptor | Enhances ligand binding to type I receptor complex |
| PIK3CA | PI3K subunit that interacts with type I receptor | Links receptor binding to non-SMAD pathways |
| PIK3R1 | PI3K regulatory subunit that binds type I receptor | Mediates PI3K activation upon receptor binding |
| BABO | Drosophila type I receptor (thickveins) binding protein | Model for studying binding specificity in vivo |
| SAX | Drosophila type I receptor (saxophone) binding protein | Model for studying binding specificity in vivo |
| TKV | Drosophila type I receptor (thickveins) | Model for studying binding specificity in vivo |
How Is type I transforming growth factor beta receptor binding Regulated?
The binding of ligands to type I TGF-beta receptors is tightly regulated at multiple levels. Extracellular regulators include ligand traps such as decorin and follistatin, which sequester ligands and prevent receptor binding. Membrane-bound co-receptors like betaglycan enhance ligand presentation to the type II receptor, indirectly promoting type I receptor binding. Intracellularly, the kinase activity of the type I receptor is inhibited by FKBP12, which binds to the GS domain and prevents ligand-independent activation. Phosphorylation of the GS domain by the type II receptor relieves this inhibition, allowing downstream signaling. Additionally, ubiquitination and degradation of receptors can modulate the duration of binding-competent receptors at the cell surface. Cross-talk with other pathways, such as PI3K/AKT, can also influence the outcomes of receptor binding.
type I transforming growth factor beta receptor binding and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| TGFBR1 | Cancer, fibrosis | Knockout or point mutation in cancer cell lines; xenograft models |
| TGFB1 | Fibrosis, cancer | Overexpression or knockout in fibroblasts; bleomycin-induced fibrosis model |
| TGFBR2 | Acute lung injury | Endothelial cell-specific knockout; LPS-induced lung injury model |
| SMAD3 | Fibrosis, cancer | Knockout mice; reporter assays for transcriptional output |
| PIK3CA | Cancer, cell growth | Knock-in of activating mutations; PI3K inhibitor studies |
Cancer
Dysregulated TGF-beta signaling, often due to altered binding of ligands to type I receptors, promotes tumor progression, epithelial-mesenchymal transition, and metastasis. Mutations in TGFBR1 or its ligands that affect binding affinity can lead to constitutive activation or loss of growth inhibition. Targeting the binding interface with small molecule inhibitors like SB505124 is a therapeutic strategy.
Fibrosis
Excessive TGF-beta binding to type I receptors on fibroblasts drives extracellular matrix deposition and fibrosis in organs such as lung, liver, and kidney. Inhibiting this binding event can attenuate fibrotic responses [4, 6].
Acute Lung Injury
Heparin-binding protein-induced acute lung injury requires TGF-beta receptor type II and subsequent type I receptor binding to activate SMAD/Rho signaling, leading to vascular leakage. Blocking this binding may reduce lung injury.
From type I transforming growth factor beta receptor binding-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of TGFBR1 abolish ligand binding and signaling? | CRISPR knockout of TGFBR1 in HEK293 or cancer cells |
| How do point mutations in the GS domain affect binding and activation? | Point mutation knock-in of TGFBR1 (e.g., T204D) |
| Can a tagged receptor be used to track binding dynamics? | Knock-in of fluorescent or epitope tag on TGFBR1 |
| What is the effect of ligand overexpression on receptor binding? | Overexpression of TGFB1 in fibroblasts or epithelial cells |
| Which genes are essential for receptor binding in a genome-wide screen? | CRISPR library screening with a binding readout |
| Can a disease-associated mutation be corrected to restore binding? | Knock-in of wild-type allele in patient-derived iPSCs |
How to Study the type I transforming growth factor beta receptor binding Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Surface plasmon resonance (SPR) | Binding affinity and kinetics | Characterizing ligand-receptor interactions |
| Isothermal titration calorimetry (ITC) | Thermodynamics of binding | Quantifying binding enthalpy and entropy |
| Phospho-SMAD immunoblot | Receptor kinase activation | Assessing signaling after ligand binding |
| SBE-luciferase reporter | Transcriptional output of SMAD activation | High-throughput screening of binding modulators |
| X-ray crystallography | 3D structure of receptor-ligand complex | Structure-based drug design |
| CRISPR knockout screen | Genes required for binding or signaling | Discovery of novel regulators |
| Co-immunoprecipitation | Protein-protein interactions | Detecting receptor complexes |
| Flow cytometry | Cell surface receptor levels | Measuring receptor availability for binding |
Biochemical binding assays
Surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC) can measure the affinity and kinetics of ligand binding to purified type I receptor ectodomains. These methods provide quantitative parameters such as KD and stoichiometry [1, 5].
Cell-based signaling assays
Luciferase reporter assays driven by SMAD-binding elements (SBE) are commonly used to measure downstream signaling after receptor binding. Phospho-SMAD immunoblotting provides a direct readout of receptor kinase activation [7, 8].
Structural biology
X-ray crystallography and cryo-EM can resolve the atomic details of the ligand-receptor complex, revealing the binding interface and conformational changes. This information is critical for rational drug design.
CRISPR-based genetic screens
Genome-wide CRISPR knockout or activation screens coupled with a binding-dependent reporter can identify novel genes that regulate type I receptor binding. These screens are powerful for discovering unanticipated modulators.
How CRISPR Can Be Used to Study GO:0034713 type I transforming growth factor beta receptor binding
Knockout
CRISPR knockout of TGFBR1 or its ligands can completely abolish binding and downstream signaling, providing a clean background to study the specific contribution of the binding event. Such models are useful for validating drug targets and understanding loss-of-function phenotypes [1, 7].
Point Mutation
Introducing point mutations in the receptor's ligand-binding domain or kinase domain can dissect the structural requirements for binding versus activation. For example, mutations in the GS domain can prevent phosphorylation and subsequent signaling without affecting ligand binding.
Knock-in
Knock-in of tagged receptors (e.g., GFP or HA) allows real-time tracking of receptor localization and binding dynamics in live cells. Knock-in of disease-associated mutations can model altered binding affinity and signaling [1, 4].
Overexpression
Overexpression of ligands or receptors can amplify binding signals and is useful for biochemical purification or for studying dose-dependent effects. However, overexpression may saturate regulatory mechanisms and should be interpreted with caution [3, 6].
How EDITGENE Supports type I transforming growth factor beta receptor binding Research
Researchers studying type I transforming growth factor beta receptor binding-related genes often need to determine whether a candidate gene is causally involved in the binding event or its downstream consequences. EDITGENE provides a comprehensive suite of CRISPR services to create precisely engineered cell models that enable such functional studies.
Contact EDITGENE today to design your custom CRISPR model for type I transforming growth factor beta receptor binding research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SMAD6 Knockout HEK293 Cell Line | EDJ-KQ126 | Human | 4091 | Details Get a Quote |
| SMAD7 Knockout HEK293 Cell Line | EDJ-KQ403 | Human | 4092 | Details Get a Quote |
| TGFB3 Knockout HEK293 Cell Line | EDJ-KQ761 | Human | 7043 | Details Get a Quote |
| SMAD2 Knockout HEK293 Cell Line | EDJ-KQ930 | Human | 4087 | Details Get a Quote |
| ENG Knockout HEK293 Cell Line | EDJ-KQ3346 | Human | 2022 | Details Get a Quote |
| LRG1 Knockout HEK293 Cell Line | EDJ-KQ3415 | Human | 116844 | Details Get a Quote |
| FERMT2 Knockout HEK293 Cell Line | EDJ-KQ7232 | Human | 10979 | Details Get a Quote |
| SNX6 Knockout HEK293 Cell Line | EDJ-KQ15409 | Human | 58533 | Details Get a Quote |
| TGFBR2 Knockout HEK293 Cell Line | EDC07591 | Human | 7048 | Details Get a Quote |
| TGFB1 Knockout HEK293 Cell Line | EDJ-KQ17770 | Human | 7040 | Details Get a Quote |
| ENG Knockout HCT 116 Cell Line | EDJ-KQ24991 | Human | 2022 | Details Get a Quote |
| ENG Knockout HeLa Cell Line | EDJ-KQ24992 | Human | 2022 | Details Get a Quote |
| FERMT2 Knockout HCT 116 Cell Line | EDJ-KQ32208 | Human | 10979 | Details Get a Quote |
| FERMT2 Knockout HeLa Cell Line | EDJ-KQ32209 | Human | 10979 | Details Get a Quote |
| SNX6 Knockout A-549 Cell Line | EDJ-KQ46185 | Human | 58533 | Details Get a Quote |
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Frequently Asked Questions About type I transforming growth factor beta receptor binding
What is GO:0034713?
GO:0034713 is a Gene Ontology molecular function term that describes the binding to a type I transforming growth factor beta receptor, a key step in TGF-beta signaling [2, 5].
What genes are involved in type I TGF-beta receptor binding?
Key genes include TGFBR1 (the type I receptor itself), TGFB1, TGFB2, TGFB3 (ligands), and accessory proteins like TGFBR2 and betaglycan [3, 4, 8].
How does type I TGF-beta receptor binding initiate signaling?
Binding of ligand to the type I receptor, often in complex with type II receptor, induces conformational changes that activate the receptor's kinase domain, leading to SMAD phosphorylation [7, 8].
What diseases are associated with abnormal type I TGF-beta receptor binding?
Dysregulation is linked to cancer, fibrosis, and acute lung injury, where altered binding promotes pathological signaling [4, 6].
What methods are used to study type I TGF-beta receptor binding?
Common methods include surface plasmon resonance, co-immunoprecipitation, phospho-SMAD immunoblotting, and CRISPR-based genetic screens [1, 6, 7].
Can CRISPR be used to study type I TGF-beta receptor binding?
Yes, CRISPR knockout, point mutation, and knock-in models allow precise dissection of the binding event and its downstream effects [1, 8].
What are the synonyms for GO:0034713?
Synonyms include TGF-beta type I binding, type I TGF-beta binding, babo binding, sax binding, and tkv binding, reflecting conserved receptors in different species.
Which type I receptors bind TGF-beta?
TGFBR1 (ALK5) is the primary type I receptor for TGF-beta, while ACVR1B (ALK4) and ACVR1C (ALK7) bind activins and related ligands.
How is type I TGF-beta receptor binding regulated?
It is regulated by accessory proteins like betaglycan, inhibitory proteins like FKBP12, and phosphorylation by the type II receptor [5, 8].
What is the role of SMAD proteins in type I TGF-beta receptor binding?
SMAD proteins are downstream effectors; upon receptor activation, they are phosphorylated and translocate to the nucleus to regulate transcription [7, 8].
Conclusion
GO:0034713, type I transforming growth factor beta receptor binding, is a fundamental molecular function that governs the initiation of TGF-beta signaling. Its precise regulation is critical for normal development and tissue homeostasis, and its dysregulation contributes to cancer, fibrosis, and other diseases. Continued research using advanced CRISPR models and biochemical assays will further illuminate the structural and functional nuances of this binding event, potentially yielding new therapeutic strategies.
References
- 1. Rodriguez Buitrago JA et al.. 2024. Human transforming growth factor β type I receptor in complex with kinase inhibitor SB505124.. Acta Crystallogr F Struct Biol Commun 80(Pt 11):314-319 PMID: 39441620
- 2. Massagué J et al.. 1992. TGF-beta receptors.. Mol Reprod Dev 32(2):99-104 PMID: 1322148
- 3. Roberts AB et al.. 1985. Transforming growth factors.. Cancer Surv 4(4):683-705 PMID: 2890434
- 4. Liu Z et al.. 2022. Transforming growth factor-β receptor type 2 is required for heparin-binding protein-induced acute lung injury and vascular leakage for transforming growth factor-β/Smad/Rho signaling pathway activation.. FASEB J 36(11):e22580 PMID: 36189652
- 5. Segarini PR. 1991. TGF-beta receptors.. Ciba Found Symp 157:29-40; discussion 41-50 PMID: 1649036
- 6. Yi JY et al.. 2005. Type I transforming growth factor beta receptor binds to and activates phosphatidylinositol 3-kinase.. J Biol Chem 280(11):10870-6 PMID: 15657037
- 7. Itoh S et al.. 2003. Elucidation of Smad requirement in transforming growth factor-beta type I receptor-induced responses.. J Biol Chem 278(6):3751-61 PMID: 12446693
- 8. Derynck R et al.. 1997. TGF-beta receptor signaling.. Biochim Biophys Acta 1333(2):F105-50 PMID: 9395284
