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Borealis Arrestin Biosensors

Signaling dynamics is a new frontier in drug discovery, involving the design of drug molecules that signal for the right time in the right place. Biosensors, like the Borealis Arrestin Sensor, have been the foundation of the latest discoveries, enabling signaling dynamics to be recorded continuously over time in live cells.

Borealis, your best-in-class fluorescent biosensor for arrestin recruitment:

  • Assess arrestin recruitment using native, unmodified GPCRs.
  • Measure kinetic cellular responses.
  • Monitor arrestin and G-limb signaling using the same modality.
  • Detect GPCR responses simultaneously or in parallel.
  • Quantify efficacy. Prioritize leads.
  • Reliably detect agonist bias in living cells.

Download easy to use modules in GraphPad Prism to convert Borealis time course data into actionable parameters that drive lead discovery.

Available Arrestin Assay Kits

Click the figure to purchase the Borealis Arrestin Kit of your choice

* Fluorescence normalized to baseline

Analyze kinetic data with intuitive Pharmechanics Tools:

  • Use the Time Course Tool Pack which provides GraphPad Prism plugins for kinetic data analysis
  • Make direct comparisons of arrestin and G-limb activity
  • Monitor the time course of GPCR activity in a single assay

A common assay modality enables reliable measurements of Arrestin and G-protein mediated signaling.

Arrestin and Ca2+ activity at the AT1R measured in parallel plates.  Assays used: Green Borealis Arrestin assay and Green GECO Calcium Assay.

Angiotensin Receptor AT1R

Arrestin Assay FAQs

What Arrestin biosensor kits are available?

Receptor-specific kits for AT1R, V2R, GLP-1R, MOP, β2AR, D1R, OTR, 5-HT2AR, KOR, PAR2, DOR, LPA1R, PTH1R, 5-HT2CR, and GCGR are shipping now.

Don’t see what you need? Please let us know

What if my receptor of interest is not available?

New receptor-specific kits will be released on a regular basis, and we do offer assay services including compound profiling and assay optimization with the Borealis Arrestin assay. These services are not limited to the receptors listed in our off-the-shelf kits. Please contact us with questions about our services, or to let us know which receptor you would be interested in investigating with these tools.

Can I use a plate reader with the Arrestin biosensor assay?

Receptors included in kits D2000G-D2140G produce robust Z’ values on standard fluorescence plate readers in HEK293T cells when used with the Borealis arrestin assay. Other cell types and receptors may require imaging to capture signals from individual cells.

Can I detect a response in primary cultures or iPSCs?

We haven’t tried iPSCs or primary cultures for the arrestin biosensors yet, but if you are interested, we can help. BacMam transduces many primary cultures, iPSCs, and cell lines well, for example publications using other biosensors in these cell types click here.

What if I have an endogenously-expressed or cell line expressing my receptor of interest?

The response will depend on a number of factors including the receptor being used, the level of receptor expression, and the profile of GRK expression. For receptors we know respond well with our Borealis arrestin sensor (FAQ 1), we recommend using the relevant receptor-specific kit so you have the GPCR and GRK, if needed, in BacMam for optimization.

For receptors that have not been optimized yet, please email us at with questions about optimization or to let us know which receptors we should test.

How do I analyze kinetic data?

Our signaling kinetics introductory video is a great starting resource.

Pharmechanics has also developed a Time Course Tool Pack which provides GraphPad Prism plugins for analyzing kinetic data. Our chapter in The Assay Guidance Manual from NIH  – Biosensor Assays for Measuring the Kinetics of G-Protein and Arrestin-Mediated Signaling in Live Cells – has additional useful information.

Can I multiplex the green arrestin biosensor with a red sensor for cAMP, DAG, or Calcium?

Yes you can. We recommend confirming the positive controls in separate experiments before multiplexing the assay.

Measuring biased agonism with a kinetic analysis platform for real time data from fluorescent biosensors

GPCR Biology

Increase your understanding of drug effects and GPCR biology with bright fluorescent assays for Gs, Gi, and Gq signaling in living cells.