The Transfluor® Assay is a cell-based fluorescence assay used to screen for G-protein coupled receptor (GPCR) ligands and other potential drugs that regulate GPCRs by deactivating or desensitizing a common pathway. By attaching a fluorescent label to beta-arrestin, the location of the receptor-arrestin complex may be monitored during receptor activation. Since desensitization only occurs with an activated receptor, monitoring beta-arrestin translocation and subsequent receptor recycling provides a method to detect the activation of any GPCR.
Studying this mechanism enables researchers to identify the impact of GPCR ligands on a variety of physiological processes including behavior, mood, inflammation, nervous system, and olfactory responses. In addition, researchers can gain insight into the complexities of receptor degradation and recycling for a given target.
- Validated with over 100 GPCRs, the Transfluor assay provides the assurance to work across all GPCR classes (Class I, II, III), regardless of interacting G-protein (Gs, Gi/o and Gq/11).
- Single read-out is compatible with all GPCR subtypes, including Gi, Gs, Go, Gq, eliminating the need for multiple GPCR assays
- No GPCR labeling or tagging avoids custom molecular biology that may alter your target's response.
- Universal format requires no prior knowledge of interacting G-protein, enabling orphan GPCR screening.
- GFP-based technology does not require additional substrates to monitor beta-arrestin translocation.
- MetaXpress® Application Module automates analysis of beta-arrestin movement to the cell membrane (pits) and endocytic vesicles.
- Ligand Independent Translocation (LITe™) Assay is an agonist-independent assay used to verify the translocation of beta-arrestin-GFP in orphan GPCRs.
With the Transfluor technology, arrestin-GFP is dispersed throughout the cytosol in unstimulated cells. Upon ligand binding with the GPCR, the arrestin-GFP quickly translocates from the cytosol to the cell membrane and then into clathrin-coated pits at the membrane. The receptor then internalizes into endocytic vesicles prior to reprocessing and returns to the cell membrane. Pits and vesicles can be imaged and quantified by commercially-available image analysis instrumentation, such as ImageXpress® Micro or ImageXpress® Ultra System, forming the basis for a universal, high-throughput, high-content assay for all GPCRs (known and orphan).
View a Transfluor technology video (4 MB MOV; requires QuickTime)
Download QuickTime player from the Apple website.
Orphan GPCR Assay
In contrast to current methods of screening GPCRs, the Transfluor technology is based on the mechanism for termination of GPCR signaling, known as receptor desensitization. This mechanism is shared by virtually all GPCRs and is activated by ligand binding. Transfluor technology requires no prior knowledge of the interacting G-protein. This important feature of the Transfluor technology makes it ideal for screening orphan GPCRs (oGPCR).
A proprietary technique to assist in validating orphan GPCR screens, called LITe™ (Ligand Independent Translocation), is an agonist-independent assay used to verify the translocation of ß arrestin-GFP in orphan GPCRs.
Garippa RJ, Hoffman AF, Gradl G, Kirsch A.
High-throughput confocal microscopy for beta-arrestin-green fluorescent protein translocation G protein-coupled receptor assays using the Evotec Opera.
Methods Enzymol. 2006;414:99-120.
Hudson CC, Oakley RH, Sjaastad MD, Loomis CR.
High-content screening of known G protein-coupled receptors by arrestin translocation.
Methods Enzymol. 2006;414:63-78.
Oakley RH, Hudson CC, Sjaastad MD, Loomis CR.
The ligand-independent translocation assay: an enabling technology for screening orphan G protein-coupled receptors by arrestin recruitment.
Methods Enzymol. 2006;414:50-63.
Haasen D, Wolff M, Valler MJ, Heilker R.
Comparison of G-protein coupled receptor desensitization-related beta-arrestin redistribution using confocal and non-confocal imaging.
Comb Chem High Throughput Screen. 2006 Jan;9(1):37-47.
Ghosh RN, DeBiasio R, Hudson CC, Ramer ER, Cowan CL, Oakley RH.
Quantitative cell-based high-content screening for vasopressin receptor agonists using transfluor technology.
J Biomol Screen. 2005 Aug;10(5):476-84.
Ozawa K, Hudson CC, Wille KR, Karaki S, Oakley RH.
Development and validation of algorithms for measuring G-protein coupled receptor activation in cells using the LSC-based imaging cytometer platform.
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Oakley RH, Hudson CC, Cruickshank RD, Meyers DM, Payne RE Jr, Rhem SM, Loomis CR.
The cellular distribution of fluorescently labeled arrestins provides a robust, sensitive, and universal assay for screening G protein-coupled receptors.
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This patented technology, licensed from Duke University, uses cell lines genetically engineered to express both the labeled beta-arrestin and the GPCR of interest and can be used to screen for natural or synthetic ligands, including agonists or antagonists. The Transfluor Assay requires no prior knowledge of the interacting G-protein, making it ideally suited for screening orphan GPCRs (oGPCR).
Partial GPCR Listing
The Transfluor technology monitors receptor activity by detecting movement of beta-arrestin-GFP in the cell. A partial listing of GPCRs that have been shown to translocate beta-arrestin-GFP is shown below.
Other Receptor Listing
- 12 Drosophila GPCRs
- Fz4 frizzled receptor
- TßRIII transforming growth factor-ß
Transfluor Assay is compatible with these systems:
For more information, view the assay kits & instrument compatibility table.
Purchase of these Transfluor products requires a prior execution of the Transfluor License agreement and the BioImage license. If ordering the GFP cell line or plasmid, a Prolume license is also required for purchase.
|Product Name||Part Number|
Transfluor® Evaluation Kit (Non Commercial Use)
Transfluor® Evaluation Kit (Commercial Use)
|U2OS (G418) rat b-arrestin 2-RrGFP parental cell lines||TF-U2OS-rBA2GFP|
Transfluor Evaluation Kit
The Transfluor Evaluation Kit enables use of the technology for a limited, one-time, six month evaluation period. The kit provides all the necessary tools for evaluating the technology with the users' own instrumentation and GPCRs. This allows users to become comfortable with the technology, before proceeding to a tiered licensing option that meets users' specific needs.
Transfluor Evaluation Kit Components
- U-2 OS β-arrestin2-GFP cells (Parental cell line, to assist with determination of the Transfluor response to end-users' choice of GPCR)
- Transfluor Demo Plate (Imaging grade plate with fixed cells to assist with instrument validation and image acquisition and analysis)
- Limited Label License
- Transfluor Evaluation Kit Product Insert
- U-2 OS β-arrestin2-GFP cells Product Insert
- Transfluor Quick Start Protocol
Transfluor User Guide (complete with protocols and troubleshooting guidelines)
Please contact your local sales representative for detailed information regarding this kit.
Tiered Licensing Options
Use of the Transfluor technology requires the purchase of a Transfluor Technology Use License from Molecular Devices which is renewable on an annual basis. A scalable license structure is available from research up to high-throughput screening including the following examples:
- Transfluor Assay Research Site License
- Transfluor Assay Research Global License
- Transfluor Screening Site License
- Transfluor Assay Research and Screening Site License
Two additional third-party licenses are required to run the Transfluor assay: a GFP license (Molecular Devices recommends the Prolume Renilla reniformis (Rr) GFP license) and BioImage's fluorescence redistribution license. Terms are as follows:
- Prolume license is renewable on an annual basis for a nominal fee.
- BioImage license is a one-time fee.
- Prolume and BioImage licenses both provide worldwide coverage.
To streamline your process, you can obtain these licenses directly from Molecular Devices. Alternatively, you can also obtain them directly from Prolume and BioImage.
Please contact your local sales representative for detailed information regarding these licenses. In conjunction with the Transfluor license, Molecular Devices also offers a stably transfected GFP beta-arrestin starter cell line and relevant plasmids.