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PhosphoSens CDK3/CycE2 Protein Kinase Assays, Substrates & Recombinant Enzymes
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About CDK3/CycE2
Cyclin-dependent kinase 3 (CDK3) is a member of the CDK family of serine/threonine kinases that orchestrate cell cycle progression, transcription, and differentiation. CDK3 requires association with cyclin E2 (CycE2) for catalytic activation, forming a complex that phosphorylates key substrates including the retinoblastoma protein (Rb) at Ser807/Ser811, histone H1, and p27/KIP1, driving the G1-to-S phase transition. CDK3/CycE2 activity is regulated by CDK-activating kinase (CAK)-mediated phosphorylation of the T-loop threonine and by endogenous inhibitors such as p21CIP1 and p16INK4a. Dysregulation of CDK3 has been implicated in melanoma, colorectal cancer, hepatocellular carcinoma, and glioblastoma, where overexpression promotes unchecked proliferation. The CDK3/CycE2 axis represents a compelling oncology drug target, particularly in tumors with Rb pathway alterations, and selectivity profiling against related CDKs (CDK1, CDK2, CDK4, CDK6) is critical for advancing next-generation CDK inhibitors with improved therapeutic windows.
Why PhosphoSens for CDK3/CycE2?
CDK3/CycE2 presents distinct assay challenges: its low endogenous abundance complicates cellular studies, and its high homology to CDK1 and CDK2 demands rigorous biochemical selectivity profiling. Endpoint methods such as ADP-Glo and HTRF capture only a single time point, masking nonlinear kinetics caused by substrate depletion, product inhibition, or tight-binding inhibitors — artifacts that frequently yield misleading IC50 values. Radiometric assays introduce safety and throughput limitations. PhosphoSens continuous fluorescent kinase assays monitor CDK3/CycE2-mediated substrate phosphorylation in real time at physiological ATP concentrations, generating full progress curves that reveal true inhibition mechanisms. Continuous kinetics enable accurate Km(ATP) determination critical for Cheng-Prusoff corrections, covalent inhibitor kinact/KI profiling, and rapid detection of slow-on/slow-off binding kinetics — capabilities essential for correctly triaging CDK3-targeted compounds in early drug discovery.
Key Pathways:
G1/S Cell Cycle Transition
Rb/E2F Signaling
CDK Regulation by CIP/KIP Inhibitors
DNA Damage Response
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How pricing works:
Select a kit or substrate below, then request a quote. Bundle discounts apply automatically.
Select a kit or substrate below, then request a quote. Bundle discounts apply automatically.
Real-Time CDK3/CycE2 Activity Assays
Continuous, real-time fluorescent assays optimized for quantitative CDK3/CycE2 activity measurements, IC50 determination, and mechanistic studies.
Assay Format: Continuous kinetic fluorescence (real-time)
PhosphoSens-Kinetic assays directly quantify enzyme activity by continuously monitoring substrate phosphorylation or dephosphorylation in real time, generating a full progress curve in every well.
Learn more about PhosphoSens-Kinetic →Need pricing or availability? Select a kit or substrate to request a quote below.
Kits
PhosphoSens-Kinetic Kinase Activity Kit - AQT0297
Ready-to-use assay kits containing substrate and all essential reagents.
Kit Contents
- Optimized PhosphoSens® substrate (AQT0297)
- ATP, DTT, EGTA, Reaction Buffer & Dilution Buffer
Automatically save 10% when bundling 10ug recombinant enzyme with your 1,000 assay kit. View enzymes
Price: $425
Substrate
PhosphoSens Kinase Substrate AQT0297
Bulk PhosphoSens® substrate for assay development and high-throughput workflows.
Specifications
Automatically save 10% when bundling Reagent Packs with your substrate. View Reagent Packs
Price: $2795
Ready to request pricing for CDK3/CycE2?
Select a kit, substrate, or enzyme above. Our team will confirm pricing, availability, and any applicable bundle discounts.
Request a QuoteNo PhosphoSens-Red format is currently available for CDK3/CycE2.
Ready to request pricing for CDK3/CycE2?
Select a kit, substrate, or enzyme above. Our team will confirm pricing, availability, and any applicable bundle discounts.
Request a QuoteNo recombinant enzymes are currently available for CDK3/CycE2.
Frequently Asked Questions: CDK3/CycE2 Assays
What substrate does AssayQuant use for CDK3/CycE2 activity assays?
AssayQuant offers optimized CSox-based peptide substrates derived from validated CDK consensus sequences, including Rb-derived motifs, that undergo a fluorescence change upon phosphorylation. These substrates enable continuous, real-time monitoring of CDK3/CycE2 activity without antibodies or secondary detection reagents, providing clean, artifact-free kinetic data.
Can PhosphoSens assays measure covalent CDK3 inhibitor kinetics?
Yes. Because PhosphoSens continuously monitors phosphorylation over time, it captures the time-dependent loss of CDK3/CycE2 activity characteristic of covalent or slow-binding inhibitors. This allows direct determination of kinact and KI parameters that endpoint assays cannot reliably measure, making it ideal for covalent CDK inhibitor programs.
How does physiological ATP concentration affect CDK3 inhibitor IC50 measurements?
Most ATP-competitive CDK3 inhibitors show strongly ATP-dependent IC50 values, so assays run at supra-physiological ATP concentrations artificially inflate apparent IC50. PhosphoSens assays are configured at physiological ATP concentrations (1-100 u00b5M range matching cellular free ATP), and accurate Km(ATP) values enable proper Cheng-Prusoff corrections, yielding Ki values that better predict cellular potency.
Data & Resources
Explore data and documents to support your kinase and phosphatase experiments. Download sample data, protocols and other resources to see how our assays perform and to help you get started in your own lab. All validation data generated using PhosphoSens® assays under recommended conditions.
Sample Report: AQT0734 - EGFR Assay Validation Report
Each validation report provides experimental conditions and data showing:
- Enzyme titration and linearity
- Sensor peptide substrate titration and Km determination
- ATP titration and Km determination
- DMSO titration and assay tolerance
- Inhibitor titration and IC50 determination
Protocol
Inhibitor IC50 Protocol
See how the PhosphoSens-Kinetic Assay can be used to find the IC50 of a kinase inhibitor.
Download Protocol →Webinar
Webinar: Continuous Assay Validation
Discover how continuous assay formats power deep understanding of kinase function. See how PhosphoSens® assays guide inhibitor profiling, selectivity assessment, and mechanistic characterization.
Watch the Webinar →Service
KinSight™ CDK3/CycE2 Profiling
Need broader selectivity data? KinSight profiling runs your compounds across our full kinase panel under identical PhosphoSens conditions.
Learn about KinSight →Stay Informed
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