GPCRs and Ion Channels

GPCRs and Ion Channels

We offer a variety of assay and instrument solutions to support studies of GPCR and ion channel function including assay kits, cellular screening and imaging systems, and microplate readers.

GPCRs (G protein-coupled receptors) are the largest protein family, with between 600 and 1000 members, and have been linked to many normal biological as well as pathological conditions. They are also known as seven transmembrane (7-TM) receptors, and about 45% of modern medicinal drugs affect this target class. The function of GPCRs is highly diverse, recognizing a wide range of ligands, including photons, small molecules, and proteins.

Ion channels are pores in the cellular membrane that allow ions to pass in and out of the cell. There are over 400 genes for ion channels in the human genome. Many of them have been targeted by drugs that are now blockbusters. Direct measurement of ion channel activity is measured using traditional electrophysiology equipment for patch-clamping. However, the throughput is very low. Ion channel activity can also be measured indirectly with much higher throughput by using fluophores sensitive to changes in membrane potential, calcium flux, and potassium flux.

Techniques of GPCRs and Ion Channels

  • Calcium Flux

    The evaluation of calcium flux is a long accepted, tried and true measure of cellular activity. Calcium flux can be used as a measurement for a host of cellular processes including neurotransmitter release, GPCR activity, voltage or ligand gated ion channels, and cardiomyocyte beat patterns, among many others. The FLIPR Tetra System is the drug discovery tool for evaluation of calcium flux in high and ultra-high throughput due to its ease of use, sensitivity and user configurability.

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  • Monitoring Gq-Coupled Protein Receptor Activity

    Gq protein-coupled receptor activation is commonly monitored in live cells in real time using calcium-sensitive dyes on a fluorescence plate reader. Automated liquid handling within the plate reader is generally required to deliver agonist compounds to the cells in the microplate while the detection system takes real-time readings of compound-induced changes in fluorescence intensity values. Analysis of the resulting kinetic readings yields information about the compound response profiles, including EC50 and IC50 values for agonists and antagonists.

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  • Live Cell Kinetic Assays

    The ImageXpress Confocal and Micro 4 High-Content Imaging Systems offer optional fluidics and environmental control modules, enabling single-channel pipetting for compound addition and media exchange during rapid kinetics or extended time-lapse experiments. The Transfluor Cell-Based GPCR Assay Kit is a valuable tool used during high content screening (HCS) to track G-protein coupled receptor (GPCR) activation by quantifying GPCR desensitization and recycling using GFP-labeled ß-arrestin with automated image analysis.

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  • Cardiomyocyte Screening

    Early prediction of drug-induced functional cardiotoxicity requires robust in vitro systems suitable for high-throughput screening. Readily-available iPSC-derived human cardiomyocytes may be used in conjunction with calcium-sensitive dyes, and beat rates are monitored as changes in intracellular calcium. These calcium peaks can be analyzed with our ScreenWorks PeakPro software which provides the investigator a suite of powerful tools for quantification of cardiomyocyte activity.

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  • Potassium Assays

    Functional evaluation of potassium ion channels in a cell is of critical importance in the drug discovery process, particularly when it involves cardiac safety. The FLIPR® Potassium Assay Kit exploits the permeability of thallium ions (Tl+) through both voltage- and ligand-gated potassium (K+) channels. In this assay, a novel, highly-sensitive Tl+ indicator dye produces a bright fluorescent signal proportional to the number of potassium channels in the open state providing a functional indication of the potassium channel activities

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  • Membrane Potential Assays

    Voltage-gated ion channels are present in the excitable cell membranes of heart, skeletal muscle, brain and nerve cells. Blocking or modulating such channels can have a therapeutic effect, or may interfere with normal cell function. As a result, compounds that affect voltage-gated ion channels are important targets in drug discovery.

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