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PhosphoSens CDK6/CycD1 Protein Kinase Assays, Substrates & Recombinant Enzymes
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About CDK6/CycD1
Cyclin-dependent kinase 6 (CDK6) is a serine/threonine kinase belonging to the CDK family that requires association with a D-type cyclin, most notably Cyclin D1, for catalytic activation. The CDK6/CyclinD1 complex is a master regulator of the G1-to-S phase transition of the cell cycle. Upon mitogenic stimulation, Cyclin D1 accumulates and binds CDK6, enabling phosphorylation of the retinoblastoma protein (Rb) and related pocket proteins p107 and p130. Rb hyperphosphorylation releases E2F transcription factors, driving expression of S-phase entry genes. Beyond cell cycle control, CDK6 exerts transcriptional functions independent of Rb, regulating NF-kB, RUNX1, and VEGF-A. CDK6 is amplified or overexpressed in numerous cancers including breast cancer, mantle cell lymphoma, glioblastoma, and leukemias. Its non-redundant role with CDK4 in specific hematopoietic and lymphoid malignancies makes CDK6 a compelling drug target, and selective CDK4/6 inhibitors have transformed the treatment of HR-positive, HER2-negative breast cancer.
Why PhosphoSens for CDK6/CycD1?
CDK6/CyclinD1 requires co-expression of an active cyclin partner, making consistent enzyme preparation and activity normalization critical assay challenges. Traditional endpoint assays such as ADP-Glo and HTRF capture only a single time point, missing the lag phase associated with Rb substrate phosphorylation and risking nonlinear kinetics artifacts. Radiometric methods introduce throughput and safety limitations incompatible with modern drug discovery campaigns. PhosphoSens continuous fluorescent kinase assays monitor CDK6 substrate phosphorylation in real time under physiological ATP concentrations, generating complete progress curves that reveal mechanism of inhibition, confirm assay linearity, and accurately determine kinact/KI for covalent inhibitors. This enables reliable selectivity profiling against CDK4 and other CDK family members, reduces false positives from inner-filter artifacts, and supports robust SAR campaigns and compound counter-screening without additional reagents or washing steps.
Key Pathways:
Cell Cycle G1/S Transition
Rb/E2F Signaling
CDK4/6-INK4-Rb Axis
PI3K/AKT/mTOR Pathway
Approved Inhibitors:
Palbociclib (Ibrance, HR+/HER2- breast cancer
Ribociclib (Kisqali, HR+/HER2- breast cancer
Abemaciclib (Verzenio, HR+/HER2- breast cancer)
Talk to a Scientist
Have questions about CDK6/CycD1 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 CDK6/CycD1 Activity Assays
Continuous, real-time fluorescent assays optimized for quantitative CDK6/CycD1 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 - AQT0258
Ready-to-use assay kits containing substrate and all essential reagents.
Kit Contents
- Optimized PhosphoSens® substrate (AQT0258)
- 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 AQT0258
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 CDK6/CycD1?
Select a kit, substrate, or enzyme above. Our team will confirm pricing, availability, and any applicable bundle discounts.
Request a QuoteTRF CDK6/CycD1 Screening Assays
Robust endpoint TRF assays optimized for high-throughput screening and quantitative CDK6/CycD1 activity measurement in plate-based workflows.
Assay Format: Time-resolved fluorescence (TRF, endpoint)
PhosphoSens-Red assays use europium-based time-resolved fluorescence detection to enable robust, plate-based quantification of enzyme activity, making them well suited for high-throughput screening workflows.
Learn more about PhosphoSens-Red →Need pricing or availability? Select a kit or substrate to request a quote below.
Kits
PhosphoSens-Red Kinase Activity Kit - AQT0258
Ready-to-use TRF assay kits containing substrate and essential reagents.
Kit Contents
- Optimized PhosphoSens® substrate (AQT0258)
- ATP, DTT, EGTA, Reaction Buffer & Dilution Buffer
- Europium Detection Solution
Automatically save 10% when bundling 10ug recombinant enzyme with your 1,000 assay kit. View enzymes
Price: $455
Substrate
PhosphoSens Kinase Substrate AQT0258
Bulk substrate for PhosphoSens-Red TRF assays 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 CDK6/CycD1?
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 CDK6/CycD1.
Frequently Asked Questions: CDK6/CycD1 Assays
What substrate does AssayQuant recommend for CDK6/CyclinD1 activity assays?
AssayQuant offers PhosphoSens CSox-based peptide substrates engineered from validated CDK6 consensus sequences, including Rb-derived peptides. These substrates produce a direct fluorescent signal upon phosphorylation without antibodies or secondary reagents, enabling continuous real-time monitoring of CDK6 activity across a wide range of ATP concentrations.
How does the PhosphoSens assay handle the requirement for Cyclin D1 co-activation of CDK6?
AssayQuant supplies CDK6 pre-complexed with Cyclin D1 to ensure consistent, reproducible catalytic activity in every experiment. Because PhosphoSens assays generate continuous progress curves, users can immediately verify that the enzyme is active and operating in a linear regime before committing compound libraries, eliminating ambiguity from endpoint measurements with partially active enzyme preparations.
Can the PhosphoSens CDK6 assay distinguish CDK6 inhibitors from CDK4 inhibitors?
Yes. Because PhosphoSens assays are run with purified CDK6/CyclinD1 or CDK4/CyclinD1 under matched conditions including physiological ATP, direct selectivity comparisons are straightforward and quantitatively reliable. The continuous kinetic readout also supports accurate Ki determination for both competitive and covalent inhibitor classes, providing high-resolution selectivity data essential for medicinal chemistry optimization.
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™ CDK6/CycD1 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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