Phospho-Tau (Ser404) cellular kit HTRF®

This HTRF kit enables the cell-based detection of phosphorylated TAU at Serine 404, as a marker of neurodegenerative diseases.

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  • Ready-to-use Ready-to-use
  • High sensitivity High sensitivity
  • Rapid Rapid
  • No-wash No-wash

This HTRF kit enables the cell-based detection of phosphorylated TAU at Serine 404, as a marker of neurodegenerative diseases.



The HTRF Phospho-TAU (Ser404) cell-based assay kit is ideal for quantifying endogenous phospho-TAU phosphorylated on Serine 404. TAU exists in different states in both Alzheimer’s (AD) and Parkinson’s (PD) diseases.

TAU hyperphosphorylation is also a marker for multiple neurodegenerative diseases and CNS disorders.



Phospho-TAU (Ser404) assay principle

The Phospho-TAU (Ser404) assay measures TAU when phosphorylated at Ser404. Unlike Western Blot, the assay is entirely plate-based and does not require gels, electrophoresis, or transfer.

The Phospho-TAU (Ser404) assay uses 2 labeled antibodies: one with a donor fluorophore, and the other with an acceptor. The first antibody was selected for its specific binding to the phosphorylated motif on the protein, and the second for its ability to recognize the protein independently of its phosphorylation state. Protein phosphorylation enables an immune-complex formation involving both labeled antibodies, and which brings the donor fluorophore into close proximity to the acceptor, thereby generating a FRET signal. Its intensity is directly proportional to the concentration of phosphorylated protein present in the sample, and provides a means of assessing the protein’s phosphorylation state under a no-wash assay format.

Phospho-TAU (Ser404) Assay principle

Phospho-TAU (Ser404) 2-plate assay protocol

The 2 plate protocol involves culturing cells in a 96-well plate before lysis, then transferring lysates to a 384-well low volume detection plate before the addition of Phospho-TAU (Ser404) HTRF detection reagents.

This protocol enables the cells' viability and confluence to be monitored.

Phospho-TAU (Ser404) 2-plate assay protocol

Phospho-TAU (Ser404) 1-plate assay protocol

Detection of Phosphorylated TAU (Ser202/Thr205) with HTRF reagents can be performed in a single plate used for culturing, stimulation, and lysis. No washing steps are required.

This HTS designed protocol enables miniaturization while maintaining robust HTRF quality.

Phospho-TAU (Ser404) 1-plate assay protocol

High phosphorylation level of TAU S404 in HEK293 cells oveexpressing Tau P301L mutant

3 million Hek293 cells were seeded in a  100mm Petri dish, and incubated for 72 hours at 37 °C - 5% CO2. 10µg of plasmid TAU P301L/30µL lipofectamine 2000 were combined with 5mL of cell culture medium and incubated for 24 hours.

After culture medium removal, cells were lysed with 1.5mL of lysis buffer for 30min at RT under gentle shaking.

Soluble fractions were then collected after a 10 min centrifugation. 16 µL of soluble fraction were transferred into a 384-well sv white microplate, and 4 µL of the HTRF detection reagents were added.

The HTRF signal was recorded after an overnight incubation.

HEK293 cells transfected with a plasmid enoding TauP301L

Phosphorylation of TAU on Ser404 is abrogated by alkaline Phosphatase treatment

50,000 human SH-SY5Y cells were plated in 96-well plates and incubated for 72h at 37 °C - 5% CO2. Medium was removed and cells were lysed with 50µl of lysis buffer for 30min at RT under gentle shaking.

Alcaline phosphatase (25U) was added with the appropriate buffer, and removed 1 hour later. 16 µL of lysate were transferred into a 384-well sv white microplate, and 4 µL of the HTRF phospho-TAU (Ser404) detection reagents were added. The HTRF signal was recorded after an overnight incubation.

alkaline phosphatase treatment on Tau Phospho S404

HTRF vs Western Blot comparison

Human SH-SY5Y cells were grown in a T175 flask at 37 °C, 5% CO2 until 80% confluency. Cell culture medium was discarded and cells were lysed with 3 mL of supplemented lysis buffer for 30 min at room temperature. Soluble fractions were then collected after a 10 min centrifugation. Serial dilutions of the cell lysate were performed in the supplemented lysis buffer and 16 µL of each dilution were dispensed and analyzed side-by-side by Western Blot and by HTRF.

Using the HTRF phospho-TAU (Ser404) cellular assay, just 2,500 cells were sufficient for minimum signal detection, while 10,000 cells were needed for a Western Blot signal.

The HTRF cellular assays are at least 4-fold more sensitive than the Western Blot.

Phospho Tau S404 HTRF versus WB

Alzheimer's disease pathway and TAU role

TAU displays a prominent role in the pathogenesis of Alzheimer's disease. It becomes hyperphosphorylated and aggregates, forming filaments, which can further condense into neurofibrillary tangles. TAU aggregates may propagate pathology by spreading from cell to cell in a prion-like manner. Drugs modulating TAU hyperphosphorylation and reducing TAU aggregation are viable therapeutic approaches.

The physiological role of TAU protein is to promote assembly and stability of microtubules. Six isoforms of TAU have been described, ranging from 352 to 441 residues coming from exons 2, 3 and 10, that are alternatively spliced. The longest isoform of TAU (TAU-441) contains 85 putative phosphorylation sites, half of which have been confirmed experimentally.

Alzheimer's disease pathway

Lysis buffer compatibility

Cell Signaling: Biomarkers, Phospho- & total-protein Assays - Flyers

Species compatibility

Cell Signaling: Biomarkers, Phospho- & total-protein assays - Flyers

HTRF Alpha-tubulin Housekeeping kit

Properly interpret your compound effect - Application Notes

Optimize your HTRF cell signaling assays on tissues

HTRF and WB compatible guidelines - Technical Notes

Key guidelines to successful cell signaling experiments

Mastering the art of cell signaling assays optimization - Guides

Unleash the potential of your phosphorylation research with HTRF

A fun video introducing you to phosphorylation assays with HTRF - Videos

How to run a cell based phospho HTRF assay

3' video to set up your Phospho assay - Videos

Best practices for analyzing brain samples with HTRF® phospho assays for neurosciences

Insider Tips for successful sample treatment - Technical Notes

Exploring Synuclein phosphorylation and aggegation with HTRF assays

Alpha Synuclein kits, perfect tools to study synucleinopathy - Posters

HTRF Product Catalog

All your HTRF assays in one document! - Catalog

A guide to Homogeneous Time Resolved Fluorescence

General principles of HTRF - Guides

Product Insert Tau P-S404 Kit / 64TS4PEG-64TS4PEH

64TS4PEG-64TS4PEH - Product Insert

Exploring LRRK2 phosphorylation with HTRF® assays

LRRK2 kit, a game changer in neuroscience - Posters

How HTRF compares to Western Blot and ELISA

Get the brochure about technology comparison. - Brochures

Best practices for analyzing tumor xenografts with HTRF phospho assays

Protocol for tumor xenograft analysis with HTRF - Technical Notes

HTRF® cell signaling platform combined with iCell® Hepatocytes

A solution for phospho-protein analysis in metabolic disorders - Posters

HTRF phospho-assays reveal subtle drug-induced effects

Detailed protocol and direct comparison with WB - Posters

Universal HTRF® phospho-protein platform: from 2D, 3D, primary cells to patient derived tumor cells

Analysis of a large panel of diverse biological samples and cellular models - Posters

HTRF phospho assays reveal subtle drug induced effects in tumor-xenografts

Tumor xenograft analysis: HTRF versus Western blot - Application Notes

HTRF cell-based phospho-protein data normalization

Valuable guidelines for efficiently analyzing and interpreting results - Application Notes

HTRF phospho-total lysis buffer: a universal alternative to RIPA lysis buffers

Increased flexibility of phospho-assays - Application Notes

Simplified pathway dissection with HTRF phospho-assays and CyBi-felix liquid handling

Analyse of PI3K/AKT/mTor translational control pathway - Application Notes

How to run a cell based phospho HTRF assay

What to expect at the bench - Videos

Molecular basis of neuroinflammation and neurodegeneration diseases

The essential guide for extending your knowledge on the molecular mechanisms of neurodegenerative diseases - Guides

HTRF cellular phospho-protein assays

Physiologically relevant results fo fast flowing research - Flyers

On-demand webinar: Linking Neuroinflammation and Neurodegeneration

New insight into neuroinflammation research - Videos

Guidelines for Cell Culture and Lysis in Different Formats Prior to HTRF Detection

Seeding and lysing recommendations for a number of cell culture vessels. - Technical Notes

Assessment of drug efficacy and toxicity by combining innovative technologies

Combination of AlphaLISA®, HTRF®, or AlphaLISA® SureFire® Ultra™ immunoassays with the ATPlite™ 1step cell viability assay - Application Notes

Methodological Aspects of Homogeneous Time-Resolved Fluorescence (HTRF)

Learn how to reduce time and sample consumption - Application Notes

Plate Reader Requirement

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