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PhosphoSens CDK3/CycE1 Protein Kinase Assays, Substrates & Recombinant Enzymes
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About CDK3/CycE1
Cyclin-dependent kinase 3 (CDK3) is a member of the CDK family of serine/threonine kinases that regulate cell cycle progression and transcription. CDK3 is activated through association with Cyclin E1 (CycE1) and requires phosphorylation of its T-loop threonine residue by CAK (CDK-activating kinase). The CDK3/CycE1 complex phosphorylates key substrates including retinoblastoma protein (Rb) at Ser807/Ser811, promoting E2F transcription factor release and G1-to-S phase transition. CDK3 also phosphorylates HDAC1 and ATF1, linking it to transcriptional regulation and stress responses. Dysregulation of CDK3 has been implicated in several cancers, including breast cancer, colorectal cancer, and skin malignancies, where overexpression drives aberrant cell proliferation. Because CDK3 shares structural homology with CDK2 yet retains distinct substrate selectivity, it represents a compelling drug target for selective anti-proliferative therapies, particularly in tumors with CDK inhibitor resistance mechanisms or elevated Cyclin E expression.
Why PhosphoSens for CDK3/CycE1?
Characterizing CDK3/CycE1 biochemically presents several challenges: the kinase exhibits low basal activity without its cyclin partner, substrate selectivity overlaps with CDK2, and physiological ATP concentrations are critical for accurate potency ranking of competitive inhibitors. Endpoint assays such as ADP-Glo and HTRF require fixed incubation times that risk product inhibition artifacts and miss non-linear kinetics, while radiometric formats raise safety and throughput concerns. PhosphoSens continuous fluorescent kinase assays monitor CDK3/CycE1 substrate phosphorylation in real time across full progress curves at physiological ATP, enabling precise kcat and Km determination, early detection of mechanism-based inhibition, and accurate IC50 and kinact/KI measurements for covalent candidates — all without antibodies or radioactive reagents, dramatically accelerating lead optimization campaigns.
Key Pathways:
Cell Cycle G1-S Transition
Rb-E2F Signaling
CDK Regulation of DNA Replication
Transcriptional Regulation by CDKs
Talk to a Scientist
Have questions about CDK3/CycE1 assay design, selectivity panels, or covalent inhibitor characterization?
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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/CycE1 Activity Assays
Continuous, real-time fluorescent assays optimized for quantitative CDK3/CycE1 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/CycE1?
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/CycE1.
Ready to request pricing for CDK3/CycE1?
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/CycE1.
Frequently Asked Questions: CDK3/CycE1 Assays
Why is it important to use physiological ATP concentrations when profiling CDK3/CycE1 inhibitors?
Many CDK3 inhibitors are ATP-competitive, and their apparent IC50 values shift substantially depending on the ATP concentration used in the assay. Using physiological ATP concentrations (~1 mM) with PhosphoSens assays ensures potency measurements reflect in-cell inhibitor behavior, improving the translatability of SAR data and preventing the under-estimation of inhibitor potency that occurs with artificially low ATP.
How does the PhosphoSens platform differentiate CDK3/CycE1 activity from closely related CDK2/CycE complexes?
PhosphoSens offers substrate peptides optimized for CDK3/CycE1 selectivity windows, and real-time progress curve analysis enables detection of subtle kinetic differences in kcat and Km that are obscured in endpoint formats. This kinetic resolution allows researchers to deconvolute inhibitor selectivity between CDK3 and CDK2 without relying on antibody-based selectivity panels.
Can the PhosphoSens CDK3/CycE1 assay be used to characterize covalent or irreversible inhibitors?
Yes. PhosphoSens continuous assays generate complete progress curves that directly report on time-dependent inhibition, enabling extraction of kinact and KI parameters essential for characterizing covalent inhibitors. This capability is not accessible with endpoint assays such as ADP-Glo or HTRF, making PhosphoSens the preferred platform for next-generation covalent CDK3 inhibitor programs.
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/CycE1 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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