GO:0005113 patched binding: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0005113 patched binding is a molecular function defined as binding to a patched (ptc) protein, the receptor for hedgehog proteins.
• Patched (PTCH1) is a sterol-sensing domain protein that inhibits Smoothened (SMO) in the absence of Hedgehog ligands.
• Hedgehog ligand binding to PTCH1 relieves inhibition of SMO, activating downstream GLI transcription factors.
• Phosphatidic acid and cholesterol/sterol binding to PTCH1 modulate its ability to inhibit SMO.
• Dysregulation of patched binding is linked to cancers such as medulloblastoma and ameloblastoma.
• CRISPR knockout, point mutation, knock-in, and overexpression models are essential to dissect patched binding mechanisms.
Description
Patched binding (GO:0005113) is a molecular function that describes the binding of a protein or ligand to a patched (ptc) protein, which is a receptor for hedgehog proteins. This term is central to understanding Hedgehog signaling, a conserved pathway that controls cell fate, proliferation, and differentiation during development and tissue homeostasis. The patched protein, encoded by PTCH1 in humans, is a twelve-transmembrane sterol-sensing domain protein that acts as the primary receptor for Hedgehog ligands such as Sonic Hedgehog (SHH). In the absence of Hedgehog, PTCH1 inhibits the seven-transmembrane protein Smoothened (SMO), preventing downstream activation of GLI transcription factors. When Hedgehog binds to PTCH1, this inhibition is relieved, allowing SMO to accumulate and signal. Thus, patched binding is not merely a passive interaction but a critical regulatory event that gates the entire pathway. Researchers study patched binding to understand developmental disorders, cancer, and to develop targeted therapeutics.
patched binding At A Glance
| GO ID | GO:0005113 |
|---|---|
| GO term | patched binding |
| Ontology | molecular_function |
| Synonym | patched ligand, ptc binding, ptc ligand |
| Major function | Binding to patched (ptc) protein, a receptor for hedgehog proteins |
| Related pathway | Hedgehog signaling pathway |
| Key proteins | PTCH1, SMO, SHH, GLI1/2/3 |
| Disease relevance | Medulloblastoma, ameloblastoma, basal cell carcinoma |
What Is GO:0005113?
According to the Gene Ontology, GO:0005113 patched binding is defined as the binding to a patched (ptc) protein, a receptor for hedgehog proteins. This molecular function encompasses interactions between patched and its ligands, including hedgehog proteins, and possibly other modulators such as sterols or phosphatidic acid that influence patched activity. The term is synonymous with patched ligand, ptc binding, and ptc ligand. It is a molecular function that occurs in the context of Hedgehog signaling and is essential for the regulation of Smoothened and downstream GLI activation.
Why Is patched binding Important in Cell Biology?
Patched binding is a fundamental molecular event that controls Hedgehog signaling, a pathway critical for embryonic development and adult tissue repair. Dysregulation of this binding leads to aberrant pathway activation, which is a hallmark of several cancers, including medulloblastoma and basal cell carcinoma. Understanding patched binding at the molecular level informs the design of Hedgehog pathway inhibitors, such as vismodegib, which target SMO but may also be influenced by patched status. Moreover, patched binding is modulated by sterols and phospholipids, revealing new layers of regulation that could be exploited therapeutically. Therefore, studying patched binding is essential for both basic developmental biology and clinical oncology.
• Controls Hedgehog signaling, a key pathway in embryonic development and tissue homeostasis.
• Mutations in PTCH1 that affect patched binding cause basal cell nevus syndrome and sporadic cancers.
• Patched binding is a target for drug discovery in Hedgehog-driven cancers.
• Sterol and phosphatidic acid binding to PTCH1 modulate patched binding and SMO inhibition.
• Patched binding is involved in ameloblastoma pathogenesis, as shown by phosphoprotein profiling.
• Proteostasis of patched and its binding partners affects pathway output.
• Structural studies of sterol-sensing domains provide insights into patched binding mechanisms.
• Chromatin modifications in medulloblastoma interact with Hedgehog signaling, including patched binding.
• Patched binding is conserved from Drosophila to humans, enabling genetic studies.
• Understanding patched binding aids in interpreting CRISPR screens targeting Hedgehog components.
Molecular Mechanism of patched binding
Hedgehog ligand binding to Patched
In simple terms: Hedgehog proteins stick to Patched, like a key in a lock.
Hedgehog ligands, such as Sonic Hedgehog (SHH), bind directly to the patched protein (PTCH1). This binding is the initial event that triggers pathway activation. The interaction occurs at the extracellular domain of PTCH1 and is essential for relieving PTCH1-mediated inhibition of Smoothened (SMO). Structural and biochemical studies have shown that Hedgehog binding induces conformational changes in PTCH1 that are transmitted to SMO.
Sterol sensing and modulation of Patched
In simple terms: Patched senses cholesterol-like molecules, which affects how it controls Smoothened.
PTCH1 contains a sterol-sensing domain (SSD) that binds cholesterol or related sterols. Sterol binding to PTCH1 is required for its ability to inhibit SMO. Mutations in the SSD that impair sterol binding disrupt patched function and lead to constitutive SMO activation. This highlights that patched binding is not limited to Hedgehog ligands but also includes sterol interactions that modulate its activity.
Phosphatidic acid binding to Patched
In simple terms: A lipid called phosphatidic acid can also bind Patched and influence signaling.
Recent studies in Drosophila have shown that phosphatidic acid (PA) binds to Patched and contributes to the inhibition of Smoothened and Hedgehog signaling. PA binding to Patched may compete with or modulate sterol binding, providing an additional layer of regulation. This finding expands the repertoire of patched binding partners beyond Hedgehog proteins and sterols.
Regulation of Smoothened by Patched
In simple terms: Patched keeps Smoothened in check until Hedgehog arrives.
In the absence of Hedgehog, PTCH1 inhibits SMO, preventing its accumulation and downstream signaling. This inhibition is mediated by direct or indirect interactions that depend on patched binding to sterols and possibly other lipids. When Hedgehog binds to PTCH1, the inhibition is relieved, allowing SMO to move to the primary cilium and activate GLI transcription factors. Thus, patched binding is a dynamic switch that controls SMO activity.
Proteostasis and trafficking of Patched
In simple terms: Patched levels and location in the cell are tightly controlled.
The abundance and localization of PTCH1 are regulated by proteostasis mechanisms, including ubiquitination and degradation. Hedgehog binding can induce PTCH1 internalization and degradation, which further amplifies signaling. Disruption of patched trafficking or stability affects its ability to bind ligands and inhibit SMO, underscoring the importance of patched binding in pathway dynamics.
Key Genes Involved in GO:0005113 patched binding
The following genes and proteins are central to patched binding and its downstream signaling.
| Gene | Major Role | Research Relevance |
|---|---|---|
| PTCH1 | Receptor for Hedgehog; binds Hedgehog, sterols, and phosphatidic acid | Mutations cause basal cell carcinoma and medulloblastoma; target for CRISPR KO and point mutation studies |
| SMO | Seven-transmembrane protein inhibited by PTCH1; activated upon Hedgehog binding | Key effector; CRISPR knock-in of SMO mutants to study resistance |
| SHH | Hedgehog ligand that binds PTCH1 | Overexpression models to activate pathway; KO to study loss of ligand |
| GLI1 | Transcription factor activated downstream of SMO | Readout of pathway activity; CRISPR KO to assess requirement |
| GLI2 | Transcription factor with activator and repressor functions | CRISPR knock-in of tagged GLI2 for localization studies |
| GLI3 | Transcription factor primarily repressor | KO models to study pathway repression |
| DISP1 | Dispatched homolog; required for Hedgehog secretion | KO to study ligand availability |
| SCUBE2 | Secreted protein that modulates Hedgehog signaling | Overexpression to enhance ligand binding |
| GAS1 | Co-receptor for Hedgehog | KO to study cooperative binding with PTCH1 |
| CDON | Co-receptor for Hedgehog | KO to study positive regulation |
| BOC | Co-receptor for Hedgehog | KO to study positive regulation |
| HHIP | Hedgehog-interacting protein; negative regulator | Overexpression to sequester ligand |
| SUFU | Negative regulator of GLI transcription factors | KO to study pathway activation |
| KIF7 | Kinesin-like protein; regulates GLI processing | KO to study ciliary trafficking |
| CHD7 | Chromatin remodeler; interacts with Hedgehog pathway | KO to study medulloblastoma progression |
| KMT2C | Histone methyltransferase; mutated in medulloblastoma | KO to study epigenetic regulation |
| PTCH2 | Patched homolog 2; may also bind Hedgehog | KO to study redundancy |
How Is patched binding Regulated?
Patched binding is regulated at multiple levels. Sterol binding to the sterol-sensing domain of PTCH1 is required for its inhibition of SMO, and mutations in this domain alter patched function. Phosphatidic acid binding to Patched can modulate its activity in Drosophila wing development. Proteostasis mechanisms, including ubiquitination and degradation, control PTCH1 levels and thus the availability of patched for ligand binding. Additionally, chromatin modifications by CHD7 and KMT2C influence Hedgehog signaling and medulloblastoma progression, indirectly affecting patched binding.
patched binding and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| PTCH1 | Basal cell carcinoma, medulloblastoma, Gorlin syndrome | CRISPR KO in keratinocytes or neural progenitors; point mutations in ligand-binding domain |
| SMO | Medulloblastoma, basal cell carcinoma; drug resistance | Knock-in of SMO mutants (e.g., D473H) to study vismodegib resistance |
| CHD7 | Medulloblastoma progression | CRISPR KO in cerebellar granule neuron precursors; overexpression of wild-type CHD7 |
| KMT2C | Medulloblastoma progression | CRISPR KO in medulloblastoma cell lines; knock-in of histone methyltransferase domain mutants |
| GLI1 | Hedgehog-driven cancers | Overexpression in fibroblasts; KO to assess pathway dependency |
Patched binding in cancer
Dysregulation of patched binding is a driver of several cancers. Inactivating mutations in PTCH1 that impair Hedgehog binding lead to constitutive SMO activation and are found in basal cell carcinoma and medulloblastoma. Medulloblastoma, a pediatric brain tumor, frequently exhibits aberrant Hedgehog signaling, and chromatin modifier mutations (CHD7, KMT2C) cooperate with patched pathway alterations to promote tumor progression. Ameloblastoma, a benign odontogenic tumor, shows altered phosphoprotein profiles that may involve Hedgehog signaling components, including patched.
Patched binding in developmental disorders
Germline mutations in PTCH1 cause Gorlin syndrome (basal cell nevus syndrome), characterized by developmental abnormalities and increased cancer predisposition. These mutations often affect the ligand-binding or sterol-sensing domains of PTCH1, disrupting patched binding and leading to inappropriate Hedgehog pathway activation during development.
Therapeutic targeting of patched binding
Small molecule inhibitors of Smoothened, such as vismodegib, are used clinically for Hedgehog-driven cancers. However, resistance can arise through mutations in SMO or downstream components. Understanding patched binding may offer alternative strategies, such as blocking Hedgehog ligand binding to PTCH1 or modulating sterol interactions.
From patched binding-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does PTCH1 ligand-binding domain mutation abolish Hedgehog binding? | Point mutation knock-in of PTCH1 in HEK293T cells |
| What is the effect of PTCH1 knockout on SMO activity? | CRISPR KO of PTCH1 in NIH3T3 cells; measure GLI reporter |
| How does sterol binding to PTCH1 affect SMO inhibition? | Knock-in of sterol-sensing domain mutants; sterol depletion assays |
| Does phosphatidic acid binding to Patched regulate Hedgehog signaling? | Overexpression of Patched mutants in Drosophila wing discs |
| What is the role of CHD7 in medulloblastoma with patched mutations? | CRISPR KO of CHD7 in patient-derived medulloblastoma cells |
| Can overexpression of SHH rescue PTCH1 loss? | Overexpression of SHH in PTCH1 KO cells; assess pathway activation |
How to Study the patched binding Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Surface plasmon resonance (SPR) | Binding affinity and kinetics between PTCH1 and ligands | Quantify effects of PTCH1 mutations on Hedgehog binding |
| Cryo-EM | 3D structure of PTCH1 and complexes | Visualize sterol binding and conformational changes |
| GLI-luciferase reporter | Hedgehog pathway transcriptional activity | Assess pathway activation in CRISPR KO cells |
| Immunofluorescence | SMO ciliary localization | Monitor pathway activation state |
| Co-immunoprecipitation | Protein-protein interactions with PTCH1 | Identify novel patched binding partners |
| Phosphoproteomics | Global phosphorylation changes | Discover signaling networks in ameloblastoma |
| CRISPR screen | Genes required for Hedgehog signaling | Identify modifiers of patched binding |
| RNA-seq | Transcriptional changes upon pathway modulation | Measure GLI target gene expression |
Biochemical binding assays
Recombinant PTCH1 and Hedgehog proteins can be used in pull-down, surface plasmon resonance (SPR), or isothermal titration calorimetry (ITC) to measure binding affinity and kinetics. These assays help quantify the effects of mutations in the patched binding interface.
Structural biology
Cryo-electron microscopy and X-ray crystallography have provided structures of PTCH1 and its complexes with sterols, revealing the sterol-sensing domain and potential ligand-binding pockets. These structures guide mutational analysis of patched binding.
Cell-based signaling assays
GLI-dependent luciferase reporters are widely used to measure Hedgehog pathway activity in cells with CRISPR-engineered PTCH1 or SMO mutations. Immunofluorescence can visualize SMO ciliary accumulation upon pathway activation.
Proteomics and phosphoproteomics
Mass spectrometry-based proteomics can identify proteins that co-purify with PTCH1 or change in abundance upon pathway activation. Phosphoproteomics of ameloblastoma samples has revealed signaling alterations that may involve patched.
How CRISPR Can Be Used to Study GO:0005113 patched binding
Knockout
CRISPR knockout of PTCH1 is used to create cells with constitutive Hedgehog pathway activation, mimicking loss-of-function mutations in cancer. Knockout of SMO or GLI genes can abolish pathway activity and test dependency. These models are valuable for drug screening and studying patched binding in a cellular context.
Point Mutation
Point mutations in PTCH1 that disrupt Hedgehog or sterol binding can be introduced via CRISPR knock-in to dissect specific binding interfaces. For example, mutations in the sterol-sensing domain (e.g., PTCH1 D584N) impair SMO inhibition and are found in basal cell carcinoma. Such models help link genotype to pathway activity.
Knock-in
Knock-in of tagged PTCH1 (e.g., GFP or HA) allows visualization and immunoprecipitation of the receptor to study its interactions and trafficking. Knock-in of reporter genes (e.g., luciferase) under GLI promoters provides a sensitive readout of patched binding activity.
Overexpression
Overexpression of wild-type or mutant PTCH1 can suppress Hedgehog signaling and is used to study dominant-negative effects. Overexpression of SHH or other ligands can activate the pathway and test the sufficiency of patched binding. These models complement knockout studies by providing gain-of-function conditions.
How EDITGENE Supports patched binding Research
Researchers studying patched binding-related genes often need to determine whether a candidate gene is causally involved in Hedgehog signaling or contributes to disease. EDITGENE provides comprehensive CRISPR services to create precisely engineered cell models, enabling functional validation of patched binding components.
Contact EDITGENE today to design your custom CRISPR model for patched binding research.
Frequently Asked Questions About patched binding
What is patched binding?
Patched binding (GO:0005113) is a molecular function defined as binding to a patched (ptc) protein, a receptor for hedgehog proteins.
What genes are involved in patched binding?
Key genes include PTCH1, SMO, SHH, GLI1, GLI2, GLI3, and co-receptors such as GAS1, CDON, and BOC.
What is the function of PTCH1 in Hedgehog signaling?
PTCH1 binds Hedgehog ligands and inhibits SMO in their absence; ligand binding relieves inhibition and activates downstream GLI transcription factors.
How does patched binding regulate Smoothened?
Patched binding to sterols and Hedgehog ligands controls the inhibition of SMO; sterol binding to PTCH1 is required for SMO inhibition.
What diseases are associated with patched binding mutations?
Mutations in PTCH1 that affect patched binding cause basal cell carcinoma, medulloblastoma, and Gorlin syndrome.
What is the role of phosphatidic acid in patched binding?
Phosphatidic acid binds to Patched and contributes to the inhibition of Smoothened and Hedgehog signaling in Drosophila.
How can CRISPR be used to study patched binding?
CRISPR knockout, point mutation, knock-in, and overexpression models allow functional dissection of PTCH1 domains and their interactions.
What are the research methods for studying patched binding?
Methods include SPR, cryo-EM, GLI-luciferase reporters, immunofluorescence, co-immunoprecipitation, and proteomics.
Is patched binding conserved across species?
Yes, patched binding and Hedgehog signaling are conserved from Drosophila to humans, enabling genetic studies in model organisms.
What cell models are available for patched binding research?
EDITGENE provides knockout, point mutation, knock-in, and overexpression cell models for PTCH1, SMO, and related genes.
Conclusion
Patched binding (GO:0005113) is a critical molecular function that governs Hedgehog signaling by mediating interactions between the patched receptor and its ligands, sterols, and lipids. Its dysregulation is implicated in developmental disorders and cancers, making it a prime target for therapeutic intervention. Advanced CRISPR models and biochemical assays continue to unravel the complexities of patched binding, offering new opportunities for drug discovery and personalized medicine.
References
- 1. Zhang Y et al.. 2023. Cellular and molecular mechanisms of Hedgehog signalling.. Nat Rev Mol Cell Biol 24(9):668-687 PMID: 36932157
- 3. Kinnebrew M et al.. 2022. Patched 1 regulates Smoothened by controlling sterol binding to its extracellular cysteine-rich domain.. Sci Adv 8(22):eabm5563 PMID: 35658032
- 4. Zhang J et al.. 2023. Phosphatidic acid binding to Patched contributes to the inhibition of Smoothened and Hedgehog signaling in Drosophila wing development.. Sci Signal 16(807):eadd6834 PMID: 37847757
- 5. Sanguansin S et al.. 2025. Phosphoprotein Profile of Ameloblastoma.. Asian Pac J Cancer Prev 26(8):3085-3091 PMID: 40849725
- 6. Liu A. 2019. Proteostasis in the Hedgehog signaling pathway.. Semin Cell Dev Biol 93:153-163 PMID: 31429406
- 7. Wu X et al.. 2022. Structural advances in sterol-sensing domain-containing proteins.. Trends Biochem Sci 47(4):289-300 PMID: 35012873
- 8. Wang W et al.. 2025. Chromatin modification abnormalities by CHD7 and KMT2C loss promote medulloblastoma progression.. Cell Rep 44(5):115673 PMID: 40393452
