GPCR Assays

Calcium and thallium flux assays for measuring the activity of many G protein-coupled receptors

G protein-coupled receptor (GPCR) assays

GPCRs (aka 7-transmembrane receptors) are a large and diverse class of transmembrane signaling proteins. They have tremendously diverse functions ranging from neurotransmitter receptors to cellular adhesion. GPCRs mediate their physiological effects in a variety of ways, most famously by coupling to downstream effectors through the heterotrimeric G protein complex (Gα,β,γ) but also through other pathways such as β-arrestins. GPCRs have been very effectively targeted for therapeutics – making up ~30% of all approved drugs. Over the last decade-and-a-half, allosteric modulation of GPCRs and unanticipated pharmacological diversity has led to a new generation of intense interest in GPCRs as therapeutic targets, therefore rapid and effective ways of measuring GPCR activation are critically important.

 

GPCR assay, purinergic receptor, kinetic fluorescence profile of calcium mobilization upon stimulation with ATP

Calcium mobilization assays for GPCRsGPCR assay using Fura-2 AM to measure calcium flux. Dose dependent response of carbachol stimulation of the endogenous muscarinic M3 receptor in HEK cells.

A key signaling pathway for many GPCRs is via Ga,q-mediated activation of phospholipase C-β resulting in generation of inositol 1,4,5-trisphosphate (IP3) and subsequent activation of IP3 receptors causing release of calcium (Ca²⁺) from intracellular stores. Using fluorescent, calcium-sensitive indicators, this signaling pathway has been exploited for decades as a rapid and effective means of measuring GPCR activation

ION offers a variety of fluorescent, Ca²⁺-sensitive indicators that are trusted for measuring GPCR activation in high-throughput screening, with microscopy or plate readers.

 

(EX 490 nm/Em 515 nm, Kd 355 nM) is the most used and the most trusted of the single-wavelength Ca²⁺ indicators. It has been the indicator of choice for countless basic research studies and has been used to screen many tens-of-millions of compounds using high-throughput screening (HTS) to discover pharmacological tools and drugs for GPCRs, and a wide variety of Ca²⁺ permeable ion channels and transporters.

(EX 490 nm, EM 515 nm) High-throughput, no wash thallium (Ca²⁺) assay. The most flexible solution for measuring the activity of GPCRs coupled to intracellular Ca²⁺ release. 10 plates

ION’s Ratiometric Calcium Essentials kit provides the necessary reagents for conducting no wash, ratiometric calcium flux assays compatible with plate reader and fluorescence microscopy applications. Individual components are provided to give the user the flexibility needed to customize your assay. Ex/Em: 340/505 nm can be used to measure Ca²⁺-bound Fura-2, and Ex/Em: 380/505 nm can be used to detect Ca²⁺-free Fura-2. 10 plates

(EX 525 nm, EM 550 nm, Kd 400nM) Brilliant Calcium Gold is a calcium flux assay for multi-well plate-based, high throughput measurements of calcium mobilization mediated through a wide variety of plasma membrane and intracellular calcium channels. The kit includes our Fluo-Gold dye, which is red-shifted for compatibility with GFP and other green fluorescent indicators. 10 plates

Thallium flux assays for GPCRs

A key signaling pathway for another major class of GPCRs, Gi/o-coupled GPCRs, is through activation of G protein-gated Inward Rectifying Potassium (K⁺) channels, better known as GIRK channels. Not only is the GPCR-mediated modulation of GIRK channels of great physiological importance, it also provides a convenient means of measuring Gi/o GPCR activity using Tl⁺ flux. This GIRK assay approach offers some key advantages compared to other approaches used to measure the activity of Gi/o GPCRs. Unlike the most common approaches which utilize fixed-endpoint measures of cAMP, the GIRK assay is a real-time measure of GPCR activation and does not require non-physiological elevations of intracellular cAMP. Unlike approaches which utilize chimeric Gα subunits (e.g. Gqi5) to induced Gi/0 GPCRs to promote intracellular Ca2+ release, the GIRK assay enables measurement of Gi/o GPCR activity through their native Gβ/γ coupling mechanism.

ION offers Tl⁺ flux reagents and assay kits to help enable researchers to utilize GIRK-based GPCR activity assays.

(EX 490 nm, EM 515 nm) is the best-in-class Tl⁺-sensitive fluorescent indicator. It displays outstanding cell loading and excellent compatibility with a wide variety of detectors including fluorescent microscopes, plate readers, and flow cytometers using commonly available FITC filters.

(EX 490 nm, EM 505 nm) A thallium flux assay adaptation designed to work with standard plate readers, microscopes, flow cytometers, and more, for measuring flux through potassium (K⁺), sodium (Na⁺), and non-selective cation channels and their effectors including transporters and GCPRs. 100 plates

(EX 490 nm, EM 505 nm) High-throughput, no wash thallium (Tl⁺) assay. The most flexible solution for measuring the activity of GPCRs using GIRK channels. 10 plates

Brilliant Thallium Gold includes Thallos Gold – ION’s gold fluorescent (Ex/Em = 528/552 nm) thallium (Tl+) indicator. Red-shifted excitation and emission enable multiplexing with GFP-expressing cells or other green fluorescent indicators. Useful for fluorescence-based potassium channel assays and for studying a wide variety of monovalent cation channels (sodium channels), transporters, and GPCRs.10 plates

Be Brilliant! Explore our line of GPCR Assays

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Ratiometric calcium assay kit, using Fura-2 AM, packaging
Combines Fura-2 AM with the necessary reagents for conducting no wash, ratiometric calcium flux assays compatible with plate reader and fluorescence microscopy applications. Individual components are provided to give you the flexibility needed to customize your assay.
340,380/505
145
$170.00-$374.00
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Min: 1
Step: 1
Fluo-4 AM calcium indicator packaging, red background
Fluo-4 is a green fluorescent, calcium indicator. Membrane-permeable. A popular solution for high-throughput calcium flux assays and GPCR assays. 
490/515
355
$68.00-$147.00
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Min: 1
Step: 1
Fluo-4 AM Ultrapure calcium indicator packaging, red background
Fluo-4 AM Ultrapure is our highest purity (>98%) grade available. Fluo-4 Ultrapure is the same green fluorescent, calcium indicator you've trusted for decades, with minimal impurities to give you maximum confidence. Membrane-permeable. The most popular solution for high-throughput calcium flux assays and GPCR assays
490/515
355
$75.00-$162.00
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Fluo-3 AM calcium indicator packaging, red background
Fluo-3 AM is a green fluorescent, calcium indicator. Membrane-permeable.
505/525
390
$78.00-$173.00
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Min: 1
Step: 1
Fluo gold, calcium indicator for calcium flux assay product packaging
Fluo-Gold is a gold fluorescent (Ex/Em = 525/550 nm), intracellular calcium indicator. Designed to measure intracellular calcium flux in high throughput screening and fluorescence microscopy applications. Fluo-Gold’s red-shifted excitation and emission enable multiplexing with GFP-expressing cells or other green fluorescent indicators, and minimizes interference from green-fluorescent compounds.
528/548
400
$88.00-$198.00
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Min: 1
Step: 1
Fluo-2 AM, a calcium indicator, packaging
Fluo-2 AM is a green fluorescent, calcium indicator. Membrane-permeable. Higher calcium affinity than Fluo-4, with superior intracellular loading.
490/515
290
$69.00-$144.00
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Fura-2 AM ratiometric calcium indicator packaging, red background
UV-excitable, ratiometric green calcium (Ca²⁺) indicator, membrane permeable
340,380/505
145
$110.00
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Min: 1
Step: 1
ICR-1, a red calcium indicator, packaging
Red fluorescent, calcium (Ca²⁺) indicator, membrane permeable. Optimal for multiplexing and tissue imaging. Fluorescence lifetime and multiphoton compatible.
580/660
480
$160.00-$352.00
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