Transcreener® cGAMP cGAS Assay Kits

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FP Manual TR-FRET Manual

Single-Step cGAS Assay for Screening and Lead Discovery

Simple - mix-and-read format
Direct detection of unlabeled cGAMP
Robust Assay Z’ > 0.7 under initial velocity conditions
Flexible - Use continuous or end-point assay methods

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Want to purchase active enzyme with your kit? Learn more about cGAS Screening Bundles.

Learn About cGAS Screening Bundles

Overview – Transcreener cGAMP cGAS Assay

Name: Transcreener® cGAMP cGAS Assay Kits
SKU: 21309
Availability: InStock

Transcreener cGAMP cGAS Assay directly measures cyclic GMP-AMP (cGAMP) produced by cyclic GMP-AMP synthetase (cGAS, C6orf150, 2’3′-cGAMP Synthetase). These cGAMP measurements allow researchers to effectively determine the enzyme’s activity. The assay provides a powerful tool to screen compound libraries for cGAS modulators to help find new therapies for disease.

The kit comes complete with the detection reagents required to measure activity. cGAS enzyme is not included in the inhibitor screening assay kit. Recombinant cGAS enzyme is available for separate purchase through BellBrook labs.

This assay is designed to be used with purified enzyme preparations. Transcreener assays are not validated with cell lysates, blood, serum, or other biological samples.

Advantages of cGAMP Detection Over

ATP Depletion Assays

Important Messenger in the STING Pathway

DNA in the cytosol of eukaryotic cells indicates infection or cellular damage, and it elicits a robust immune response, driven by type I interferon (IFN) induction.

cGAS is an exquisitely sensitive sensor for double-stranded DNA in the cytoplasm. Binding of DNA activates the enzyme to produce a unique cyclic dinucleotide second messenger, cGAMP, which acts as an agonist for the STING (stimulator of interferon genes) receptor, leading to induction of a type I interferon response.

How Does This cGAS Assay Work?

The Transcreener cGAMP cGAS Assay determines cGAS enzyme activity by directly measuring the cGAMP formed by the enzyme using the Transcreener cGAMP Assay. By detecting cGAMP output, the assay provides a universal method to assess the activity of any cGAMP-producing enzyme in real-time.

Transcreener cGAMP Assay technology uses a simple but highly effective method that consists of an antibody selective to cGAMP and a far-red fluorescent tracer. cGAMP produced in the reaction competes with the tracer changing the fluorescent properties and providing fluorescent readout.

The cGAS assay is available with FP and TR-FRET. It is a simple mix-and-read format. Perform your enzyme reaction, add the detection reagent, and measure. The simplicity of the system yields robust results that also makes it extremely amiable to HTS.

Far-Red FP & TR-FRET Readouts Validated on Major Multimode Readers

Targeting the cGAS-STING Pathway Using a Homogenous, HTS Compatible Transcreener cGAS Assay

Specifications

What’s Included

FP
	1K		10K
Component	Part #	Qty	Part #	Qty
cGAMP Antibody, 1.8 mg/mL	2196	15 µL	2197	111 µL
cGAMP Atto 633 Tracer, 800 nM	2194	100 µL	2195	1 mL
5 mM ATP	2200	600 µL	2201	6 mL
5 mM GTP	2202	600 µL	2203	6 mL
500 uM cGAMP	2198	40 µL	2199	400 µL
25 µM Interferon Stimulatory DNA	2204	24 µL	2205	240 µL
Stop & Detect Buffer B, 10X	2027	1 mL	2032	10 mL

TR-FRET
	1K		10K
Component	Part #	Qty	Part #	Qty
cGAMP Antibody-Tb, 800 nM	2235	100 µL	2236	1 mL
cGAMP ATTO 647 Tracer, 800 nM	2237	200 µL	2238	2 mL
5 mM ATP	2200	600 µL	2201	6 mL
5 mM GTP	2202	600 µL	2203	6 mL
500 µM cGAMP	2198	40 µL	2199	400 µL
25 µM Interferon Stimulatory DNA	2204	24 µL	2205	240 µL
Stop & Detect Buffer C, 10X	2062	1 mL	2065	10 mL

What You Will Need

Component	Notes
cGAS Enzyme	You can purchase active *cGAS enzyme* directly through BellBrook Labs.
Enzyme Buffer	We routinely use enzyme buffer containing 20 mM TRIS (pH 7.5), 5 mM MgCl₂, 0.01% Brij-35, and 1% DMSO (test compound solvent). Use the buffer that is a best fit for your enzyme conditions
Assay Plates	Assay Plates Can Be Purchased Separately From BellBrook Labs. FP - An entirely black plate with a non-binding surface is required. We suggest Corning 384-well plates (Cat. #4514) or 1536-well plates (Cat. #3728). TR-FRET - An entirely white plate with a non-binding surface is required. We suggest Corning 384-well plates (Cat. #4513) or 1536-well plates (Cat. #3729).
Plate Reader	A multi-detection plate reader configured to measure the output of the cGAMP tracer is required.
Enzyme Buffer	Use liquid handling devices that can accurately dispense sub-microliter volumes into 384-well plates.
Ultrapure Water	Some deionized water systems are contaminated with nucleases that can degrade both nucleotide substrates and products, reducing assay performance. Careful handling and use of ultrapure water eliminates this potential problem.

Applications

Measure Enzymatic Activity of cGAS
Screen Compound Libraries for cGAS inhibitors
Quantify Inhibitor Potency

Determine Inhibitor-cGAS Residence Time

Features

Direct detection of unlabeled cGAMP
Easy to use, homogenous, one step format
Robust Assay Z’ > 0.7 under initial velocity conditions
Far-red fluorescent readouts minimize compound interference
A safe, non-radioactive method
Available in FP or TR-FRET readouts

Easy-to-Use, Mix-and-Read, HTS-Ready Assay

Run your enzyme reaction, add Transcreener reagents, and read your plates. The cGAS assay is compatible with 96, 384, and 1536-well formats.

Outstanding Signal Stability

The assay exhibits 24 hours+ signal stability. Plate stability like this is vital for sizeable high throughput screens that take significant time to complete due to massive sample quantity.

Standard curves include ATP, GTP, dsDNA, and titration of cGAMP. The same plate was read at each time point.

Direct Detection of cGAMP to Measure cGAS Enzymatic Activity

The assay demonstrates linearity when raw data is converted to cGAMP using a standard curve. cGAS is activated by double-stranded DNA and requires ATP and GTP substrates for the production of cGAMP.

Full-Length Human cGAS Titration

Linear Response

cGAS Enzyme Titration Initial Velocity Conditions

Screen for Inhibitors & Perform SAR

The Transcreener cGAS Assay is designed for screening compound libraries in a high throughput format. Follow up SAR can also be performed using the assay to determine inhibitor potency with ease.

1600 Compound Pilot Screen

Dose Response Measurements

Yields Accurate Dose Response Results with Known cGAS Inhibitor, G150

Example dose response curves using known cGAS inhibitor, G150. Assay conditions include 100 μM ATP, 100 μM GTP, 100 nM ISDNA, 20 mM Tris (pH 7.5), 5 mM MgCl₂, 0.01% Brij-35 (pH 7.5). The enzyme reaction took place for 60 minutes at room temperature. The FP Detection Mix included 1X Stop & Detect Buffer B, 8 nM cGAMP 633 Tracer, and 2.0 μg/mL cGAMP antibody. The TR-FRET Detection Mix included 1X Stop & Detect Buffer C, 16 nM cGAMP ATTO 647 Tracer, and 8 nM cGAMP Antibody-Terbium. The Detection Mix was incubated for 1 hour at room temperature.

FP Readout

IC₅₀ = 0.04 μM

TR-FRET Readout

IC₅₀ = 0.05 μM

Illustrates DNA & Substrate Dependance of the cGAS Enzyme

The assay accurately demonstrates the characteristics of the cGAS enzyme. Double-stranded DNA activates the enzyme which generates cGAMP in the presence of both GTP and ATP. A 45 base pair ISD (interferon stimulatory DNA) and a 60 base pair HSV (herpes simplex virus) DNA both activate the enzyme. The assay has a high affinity to cGAMP and can detect even in the presence of other nucleotides.

cGAS Enzyme Activation by dsDNA

Dependence on ATP and GTP

BellBrook Lab’s Recombinant cGAS Enzyme

Active, full-length Human Cyclic GMP-AMP synthase enzyme, His-tagged protein expressed and purified from E.coli. The enzyme has been thoroughly validated with Transcreener cGAS Activity Assays. For specific activity, please refer to the Certificate of Analysis for each individual enzyme lot. Purity is >90% in a 20 mM Tris 7.5, 200 mM NaCl, 1mM DTT, 10% glycerol buffer composition. The enzyme is currently used in the Transcreener cGAS Activity Assay at 30 nM, which is 1.75 μg/mL (17.5 ng in 10 µL enzyme reaction volume in a 384-well format). Please adjust the enzyme concentration based on your requirements.

Go to Human cGAS Enzyme Page

cGAS Assay Services

Interested in moving your program forward, but don’t want to bring an assay in-house? Our scientists can help! BellBrook scientists will use their extensive biochemistry and enzymology expertise to work with you and accelerate your cGAS program.

Lead Discovery Services Include:

Inhibitor Screening – To identify or confirm activity with the target.
Inhibitor Potency Profiling – Dose-response with target and/or related proteins. Fast IC₅₀ results.
Residence Time Measurements – Determination of k_off using ‘jump dilution’ enzymatic assay method.
Mechanism of Action Studies – Kinetic analysis to define the mode of inhibition.

Contact Us for Services

Please fill out the form below. We will respond quickly to get the conversation moving and learn how we can help. We keep things discrete, confidential, and professional.

Interconnections Between the DNA Damage Response and Innate Immunity

There is extensive crosstalk between the DNA damage response (DDR) pathways and innate immune pathways. Both the individual pathways and the interconnections between them are a focus for exciting new small molecule drug therapeutics that target cancers and debilitating autoimmune disorders. The Transcreener HTS Assay platform accelerates these efforts by providing a robust and easy-to-use biochemical assay to measure activity of key enzymes in the innate immune and DDR pathway.

In this guide, we provide an overview of the DDR and innate immune pathway, and describe Transcreener Assays and Assay Systems for key therapeutic targets. The enzyme targets discussed include:

DDR

POLQ
WRN
PARP1
PARG
DNA PK

Innate Immunity

cGAS
TREX1
TBK1
IKKβ
IRAK4
ENPP1
CD38
OAS-1
RIG-I/MDA5
DDX3
CD39
CD73

The Role of cGAS As a Therapeutic Target

cGAS recognizes foreign double-stranded DNA and initiates an innate immune response, called the cGAS-STING pathway. cGAS can cause tissue or autoimmune diseases if overactivated by the body’s abnormal DNA. Examples of diseases caused by this include Aicardi-Goutières syndrome, systemic lupus erythematosus, and primary biliary liver disease (Li et al, 2021).

The cGAS-STING pathway is an attractive target for autoimmune diseases and cancers. Transcreener’s cGAMP cGAS Assay is an excellent tool for researchers examining the therapeutic effects of cGAS.

Related Resources

Resources

Find the right resources to help you get to your solution faster.

FAQ

Protocols

Publications

Instrument Compatibility

Application Notes

Posters

Contact Us to Learn More

Please fill out the form below. We will respond quickly to get the conversation moving and learn how we can help. We keep things discrete, confidential, and professional.

“Some CROs reserve their best teams for high profile customers. If you’re not right there with them you get less experienced teams… BellBrook understands enzyme kinetics, so it made that part of the project so much easier. The larger CRO didn’t seem to have the expertise we needed in this area.”

- BioPharma Lead Discovery Program Manager

“The ADP assay is a great choice for measuring activity for any ADP-generating enzyme in both real time and endpoint formats. The universal detection system has been very useful for more challenging targets.”

- Pharmaceutical Research Scientist

“Excellent blend of simplicity & good science. Excellent technical support”

- Director Pharma Drug Discovery Center

“The assay itself has good reproducibility and provides a clear readout on our enzyme activity. The most important piece, however, is the level of attention to our project and rapid turnaround time. The staff at BellBrook knows what they are doing.”

- Biotech Program Manager

“The Transcreener AMP/GMP Assay is extremely straightforward to use and is very sensitive. In a UV-based enzyme assay I needed 1 µM enzyme to see a decent signal; however using the Transcreener AMP assay I only need 10 nM. Also, BellBrook Labs have been very helpful with the assay development. Their representative has been very willing to quickly help me get my assay up and running.”

- University Research Scientist

“Through the process of developing and validating an assay for HTS applications, I generated a very nice data package of robust high quality data.”

- Biotech Research Scientist

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Frequently Asked Questions

What makes the Transcreener cGAMP cGAS Assay Kit different from other cGAS assays?

It directly detects cGAMP—your enzyme’s product—using a highly selective antibody in a simple mix‑and‑read format. This eliminates coupling steps, reduces false positives, and delivers rapid, reliable screening data.

Can I screen compound libraries or profile inhibitor potency with this kit?

Yes. The assay measures cGAS enzymatic activity and supports inhibitor screening, potency quantification, and residence-time studies—all in an HTS-compatible format.

Which detection modes are supported?

You can choose between fluorescence polarization (FP) and TR‑FRET readouts, both offering robust data quality (Z’ ≥ 0.7) and compatibility with most plate readers.

Is the kit suitable for high-throughput screening (HTS)?

Absolutely. It has been validated for workflows in 96-, 384-, and 1536-well formats and provides excellent data stability (signal remains stable for over 24 hours), making it ideal for automated HTS campaigns.

How do I get started with the Transcreener cGAMP cGAS Assay Kit?

You can request a sample, download the technical manual, or schedule a consultation with our scientists to discuss your cGAS assay setup and readout preferences.

BellBrook Labs
1232 Fourier Drive, Suite 115
Madison, Wisconsin 53717 USA
(608) 443-2400

info@bellbrooklabs.com

Also required (not included):

Recombinant cGAS Enzyme, Human, Full-Length – 10 µg