Tanso Biosciences' proprietary GPCR functional assay technology enables high-sensitivity and comprehensive evaluation of GPCR activity across all receptor types. By combining engineered assay cells, a versatile Gα protein cocktail, and a comprehensive GPCR library, our platform supports orphan receptors and all major G protein pathways under a unified assay format.
- 1. About GPCRs: The Most Targeted—Yet Least Explored—Receptors
- 2. Our Platform: All-Around Functional Assays That Just Work
- 2.1. Components
- 2.1.1. Proprietary Assay Cells
- 2.1.2. Gα protein cocktail
- 2.1.3. Comprehensive GPCR library
- 3. What You Can Do With It: Applications
- 4. Validation
- 4.1. AGTR1, a peptide-ligand receptor
- 4.1.1. Tanso's method
- 4.1.2. Inositol phosphate formation
- 4.1.3. Binding assay
- 4.2. GPR91, a low molecular ligand receptor
- 4.2.1. Tanso's method
- 4.2.2. Ca2+ assay
- 4.3. Flt3, a receptor tyrosine kinase (RTK)
- 4.3.1. Tanso's method
- 4.3.2. Cell proliferation
- 4.4. Reproducibility
- 5. Conclusion
- 6. FAQs
About GPCRs: The Most Targeted—Yet Least Explored—Receptors
G-protein-coupled receptors (GPCRs) are a highly diverse class of membrane receptors that play critical roles in human physiology. With approximately 800 members in the human genome, they are the largest group of receptors and regulate a wide range of biological processes, including blood pressure, blood glucose levels, and cognitive functions. Out of these 800 GPCRs, approximately 200 respond to endogenous mediators, while the remaining 500 function as sensory receptors, detecting smells, tastes, and other stimuli. The last 100 GPCRs remain unclassified, with their ligands yet to be identified.
GPCRs have been a prime target for drug discovery, particularly receptors for endogenous mediators. One-third of drugs in the market target GPCRs. It is because many diseases, such as cardiovascular and neurological disorders, involve the dysregulation of these receptors. In addition, recent studies have shown that orphan and sensory receptors also play important roles in various pathophysiology. These findings highlight the vast untapped potential of the majority of GPCRs in the field of drug development.
Despite their promise, however, only a small portion of GPCRs have drugs developed to target them. The lack of adequate and reliable assays has been a barrier to GPCR drug discovery. Current binding assays suffer from false positives and false negatives, and functional assays have limitations, such as being time-consuming, expensive, or limited in their applicability. Additionally, the G12/13 and Gi/o subtypes of G-proteins are notoriously intractable and further complicate GPCR research.
Tanso Biosciences has developed a high-performance functional assay to overcome these barriers and make high-hanging GPCRs accessible to the pharmaceutical industry. Our core technology combines sensitive and versatile reporter cells, a comprehensive Gα protein cocktail, and a comprehensive human and mouse GPCR library to make possible functional assays of all GPCRs.
Our Platform: All-Around Functional Assays That Just Work
Our cell-based GPCR functional assay has the following key features:
- Ultra-sensitive for detecting GPCR signaling
- Validated across 550 GPCRs (300 human, 250 mouse)
- Compatible with all four G protein subtypes (Gs, Gi/o, Gq/11, G12/13)
- Effective for orphan GPCRs and cross-species orthologs
- Rapidly deployed and fully customizable
Patent granted in JP and US (WO/2020/026979) | Published use case in Diabetes Res Clin Pract. 2025
Components
The core technology for our cell-based GPCR functional assay consists of sensitive and versatile test cells, a Gα protein cocktail, and an exhaustive human GPCR library.
Proprietary Assay Cells
Our proprietary assay cells are equipped with an artificial gene circuit that amplifies GPCR-induced intracellular signals, resulting in highly sensitive and specific results. These cells can work with all major Gα proteins, including Gq, Gs, Gi/o, and G12/13. The cells have been verified with 99% (208 out of 210) of non-orphan GPCRs. Furthermore, they have proved themselves in assays with other membrane receptors, such as receptor tyrosine kinases. This technology has been patented in Japan and the US, and is currently pending in Europe (Publication Number WO/2020/026979).
Gα protein cocktail
The all-around Gα protein cocktail complements our proprietary assay cells and enables functional assays for any GPCR under a single protocol, regardless of the Gα protein the target receptor is coupled with.
Comprehensive GPCR library
Our comprehensive GPCR library is an industry-leading collection of non-sensory GPCRs, using native sequences to minimize signal artifacts. The library includes 206 non-orphan human GPCRs and 94 orphan GPCRs, 187 non-orphan mouse GPCRs, and 63 orphan mouse GPCRs, totaling 300 human and 250 mouse receptors. Visit our GPCR Catalog for further details.
GPCR Catalog
Vast collection of 300 human GPCRs and 250 mouse GPCRs with hundreds of concentration-response curves and more.
What You Can Do With It: Applications
| Application Area | What We Offer |
|---|---|
| 🔍 Ligand Screening | Including orphan GPCRs and non-human orthologs |
| ⚖️ SAR Analysis | Concentration-response curves and receptor profiling |
| 🧬 Off-Target & Safety Profiling | Across large GPCR panels and species |
| 🔄 Lead Optimization | Insightful data to inform hit expansion and candidate selection |
| 🌐 Interspecies Comparison | For translational research and model organism bridging |
| 🧪 Assay Formats | Panel assays, therapeutic area-specific profiling, and custom formats |
Validation
Our assay has yielded consistent readouts with results from existing methods and at high sensitivity and S/B ratio. Also, the results are consistent, whether tests are performed by different experimenters or on different days. In the figure, we measured EC50 values for 116 human GPCRs and compared them with EC50 or dissociation constants curated by IUPHAR.
We compared our assay and existing methods using a few representative GPCRs below.
AGTR1, a peptide-ligand receptor
Tanso's method
Binding assay
| Ligand | Ki (nM) ± s.e.m. | n |
|---|---|---|
| Sar1-angiotensin ⅠⅠ | 0.38 ± 0.07 | 3 |
| Sar1, Ala8-angiotensin ⅠⅠ | 0.43 ± 0.08 | 3 |
| Sar1, Ile8-angiotensin ⅠⅠ | 0.46 ± 0.03 | 3 |
| Ile7-angiotensin ⅠⅠⅠ | 1.1 ± 0.3 | 3 |
| Angiotensin ⅠⅠ | 1.6 ± 0.2 | 3 |
| Angiotensin ⅠⅠⅠ | 5.4 ± 0.5 | 3 |
| Dup753 | 6.3 ± 0.9 | 3 |
| Angiotensin Ⅰ | 74 ± 12 | 3 |
| Arg8-vasopressin | >1,000 | 2 |
| Endothelin | >1,000 | 2 |
| PD123177 | >10,000 | 2 |
GPR91, a low molecular ligand receptor
In our assay, GPR91 responded to its agonist at high sensitivity and S/B ratio and consistently with the results from existing methods.
Tanso's method
Ca2+ assay
Flt3, a receptor tyrosine kinase (RTK)
Tanso's method
Cells from the same line of test cells were used in this assay as in assays for GPCRs, and Flt3 was transiently transfected into cells in the same way as GPCRs.
Reproducibility
Reproducibility is key when it comes to pharmaceutical research. Tanso Biosciences' GPCR functional assay is not only sensitive and versatile but highly reproducible. We conducted a series of experiments to verify the consistency of our assay, and the results were impressive.
First, we performed concentration-response analyses for β1 adrenoceptor (ADRB1) vs. isoproterenol on three different days (Figure 1, Table 1). Each test yielded a very close EC50 value, indicating excellent reproducibility of the assay.
This figure displays the results of three independent tests conducted on different days, in which ADRB1-expressing reporter cells were treated with the receptor agonist isoproterenol (n = 4, mean ± SEM). The data were fitted to sigmoid curves with a common Hill coefficient.
| Test | EC50 | Hill coefficient |
| 1 | 33 nM | 2.8 |
| 2 | 36 nM | 2.8 |
| 3 | 31 nM | 2.8 |
| Aggregate | 33 nM | 2.8 |
Next, we examined the variability between experimenters. Two experimenters in our lab conducted concentration-response analyses for type 1 angiotensin 2 receptor (AGTR1) and yielded comparable results both in the agonist mode (Figure 2, Table 2) and the antagonist mode (Figure 3, Table 3).
This figure displays the results of identical tests conducted by two experimenters, in which AGTR1-expressing reporter cells were treated with the receptor agonist angiotensin II (n = 4, mean ± SEM). The data were fitted to sigmoid curves with a common Hill coefficient.
| Experimenter | EC50 | Hill coefficient |
| 1 | 160 pM | 2.0 |
| 2 | 120 pM | 2.0 |
| Aggregate | 140 pM | 2.0 |
This figure displays the results of identical tests conducted by two experimenters, in which AGTR1-expressing reporter cells were treated with the receptor antagonist valsartan in the presence of angiotensin II (n = 4, mean ± SEM). The data were fitted to sigmoid curves with a common Hill coefficient.
| Experimenter | IC50 | Hill coefficient |
| 1 | 2.1 nM | -1.4 |
| 2 | 2.4 nM | -1.4 |
| Aggregate | 2.2 nM | -1.4 |
Overall, our verification process demonstrated that Tanso Biosciences' GPCR functional assay consistently produces reliable results, regardless of who conducts the test or when it is conducted. Trust in the reproducibility of our assay and choose Tanso Biosciences for your research needs.
Conclusion
In conclusion, Tanso Biosciences has made significant advancements in the field of GPCR research with its high-performance functional assay. This assay offers a solution to the current limitations in GPCR drug discovery, allowing for the development of drugs targeting all GPCRs, including both non-orphan and orphan receptors, coupled with any major Gα proteins. With its remarkable sensitivity and vast receptor coverage, this assay is poised to be a valuable tool in the pharmaceutical industry's pursuit of innovative drug development.
FAQs
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What are GPCRs, and why are they important in drug discovery?
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GPCRs are a class of membrane receptors that play a critical role in regulating various biological processes in the human body. With around 800 members in the human genome, they are the largest group of receptors. They are a prime target for drug discovery due to their role in regulating blood pressure, blood glucose levels, and many other functions.
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What is Tanso Biosciences' cell-based GPCR functional assay?
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Tanso Biosciences' cell-based GPCR functional assay is a high-performance assay that enables functional assays of all major GPCR types. It combines proprietary assay cells, a comprehensive Gα protein cocktail, and a comprehensive human GPCR library to make functional assays possible for all GPCRs, including non-orphan and orphan receptors, regardless of the subtype of coupled Gα proteins.
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How does Tanso Biosciences' GPCR assay differ from other assays in the market?
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Tanso Biosciences' functional assay has several key features that set it apart from other assays in the market. These include remarkable sensitivity and signal-to-background ratio, an exhaustive library of 550 human and mouse GPCRs, and the ability to work with all major Gα proteins, including Gq, Gs, Gi/o, and G12/13.
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Which applications are supported by your assay platform?
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We support a broad spectrum of drug discovery applications, including:
- Ligand screening (including for orphan GPCRs)
- SAR analysis
- Lead optimization
- Off-target safety profiling
- Interspecies comparison
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Do your reporter cells amplify noise as well as signals?
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The artificial gene circuit in our cells is designed to amplify signals quadratically while boosting noise only by ~two-fold. The cells have responded to stimuli with >100-fold signal/background ratios and small standard errors in many GPCRs（see Validation).
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What animal species are supported?
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We provide validated assays for 300 human and 250 mouse GPCRs. Our system is expandable to orthologs from other species, allowing cross-species pharmacology studies.
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Is your technology patented or published?
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Yes. Our core assay platform is protected under international patents (JP & US, WO/2020/026979), and the technology has been applied in peer-reviewed research (Diabetes Res Clin Pract. 2025;222:112094).
Contact Us
We welcome quotation requests and inquiries about our assay services, custom assay development, or co-development opportunities. Visit Contact Us for the ordering process and the inquiry form. Our team will respond within 24 hours.