Learn More About Transcreener Method Used for This JAK3 Assay

Discover JAK3 Modulators with the Transcreener ADP2 Assay

The Transcreener ADP² Kinase Assay directly measures the ADP produced by JAK3 (also known as Janus Kinase 3). By measuring the production of ADP researchers can effectively determine the activity of the JAK3 enzyme. The assay provides a powerful tool to screen compound libraries for JAK3 modulators to help find new therapeutics for a variety of different conditions including autoimmune diseases and cancer.

The kit comes complete with all the detection reagents required to measure activity. JAK3 enzyme is not included in the inhibitor screening assay kit. Please contact us for questions related to acquiring the enzyme.

The Role of JAK3 As Therapeutic Target

JAK3 is a tyrosine kinase that is activated by cytokine receptors. These cytokines include IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21. JAK3 can also autophosphorylate in the presence of ATP; examples of that can be seen in the data below. JAK3 phosphorylates and activates STATs that induce the expression of genes in the cell nucleus.[1]

Recent research has shown that JAK3 activation is common in many different cancers and that JAK3 autophosphorylation could be a rate-limiting step. [2] JAK3 mutations have been identified in different forms of leukemia and lymphoma. Inhibiting JAK3 or JAK1 could provide a potential treatment for these cancers. [3]

Because it is expressed only in hematopoietic cells, which should help to limit off-target effects, JAK3 is also being vetted for autoimmune diseases like rheumatoid arthritis.[4] A JAK1 and JAK3 inhibitor, Tofacitinib is currently marketed by Pfizer. New specific JAK3 inhibitors could help limit the current off-target effects of the drug.

Direct Detection of ADP to Measure JAK3 Enzymatic Activity

ADP FP Kinase Assay

The workhorse. Used in many large screens. Best deck and signal stability.

ADP FI Kinase Assay

Positive FI signal. Compatible with simple fluorescence plate readers. Faster read time than FP or TR-FRET.


For customers who prefer TR-FRET detection. Uses the same filter set as HTRF®.


  • Measure Enzymatic Activity of JAK3
  • Screen Compound Libraries for JAK3 Modulators
  • Quantify Inhibitor Potency
  • Inhibitor Selectivity Profiling
  • Measure Drug-Target Residence Time


  • Direct detection of unlabeled ADP
  • 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, FI, or TR-FRET readouts

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

The Transcreener ADP² JAK3 Assay is in a simple, HTS-ready, mix-and-read format. Run your enzyme reaction, add Transcreener reagents, and read your plates. The assay is compatible with 96, 384, and 1536-well formats.

Detection of ADP Under JAK3 Initial Velocity - FP Readout

The assay demonstrates linearity when raw data is converted to ADP using a standard curve. Here we use 10 µM ATP with 20 µM JAK3tide peptide substrates. Linearity is shown here under initial velocity conditions when raw data is converted to ADP formed. The JAK3 enzyme reaction took place for 60 minutes at room temperature. The enzymatic reaction was then halted using Stop & Detect Buffer B included in the kit and assay plates were read. Non-productive hydrolysis of ATP occurs in many kinase reactions due to many factors including autophosphorylation and water exploiting the ATP binding pocket of the enzyme.

Human JAK3 Enzyme Titration

JAK3 Assay Enzyme Titration

Linear Response

Screen for Inhibitors & Perform SAR

Transcreener Assays are 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. Assay conditions include 3 nM JAK3, 10 µM ATP, 0.2 µg/µL Poly(Glu-Tyr, 4:1) substrate for an enzyme reaction of 60 minutes at room temperature.

Dose-Response - Staurosporine

JAK3 Staurosporine Inhibitor Titration

IC50 = 1.814 nM

Robust Assay Yields Quality Data

Z’ measurements using optimized JAK3 reaction conditions indicate a robust assay.  Robust data like this is vital for sizeable high throughput screens that are difficult to complete due to massive sample quantity. Both reactions have 105 μM ATP and 0.2 μg/μL Poly (Glu-Tyr, 4:1). Z' shown here = 0.75.

Three Fluorescent Readouts Available

Choose the readout that is the best fit for your lab based on preference and plate reader compatibility. 

Fluorescent Intensity

JAK3 Enzyme Titration FI Readout

Assay conditions for the JAk3 titration shown include 10 µM ATP, 0.2 µg/mL Poly (Glu-Tyr, 4:1), and 11 µg/mL ADP² antibody in the detection mixture.


Assay conditions for the JAK3 titration shown include 10 µM ATP, 0.2 µg/mL Poly (Glu-Tyr, 4:1),  27 nM tracer, and 8 nM ADP² Tb Antibody in the detection mixture.

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

What's Included

What You Will Need