TaqMan® Protein Assays are an adapted form of PLA™, a proximity ligation assay technology [1,2] that combines antibody-protein binding with detection of the reporter nucleic acid by real-time PCR. We have optimized this technique for use with crude cell and tissue lysates and employ TaqMan® Assays to offer a highly sensitive and specific process for measuring protein expression in small samples.

There are two product choices for TaqMan® Protein Assays–based research

  • Predesigned TaqMan® Protein Assays
    Predesigned TaqMan® Protein Assays were developed for the detection of OCT3/4, NANOG, SOX2, and LIN28 in human embryonic stem cells, as well as ICAM1 and CSTB to measure relative quantification in human cells.
  • Custom TaqMan® Protein Assay Using Your Antibodies
    The TaqMan® Protein Assays Open Kit includes everything you need, except antibodies to your protein of interest, to build your own TaqMan® Protein Assay.

Choose from Predesigned TaqMan® Protein Assays

TaqMan® Protein Assays help quantitate protein expression using gold standard TaqMan® 5- nuclease assay chemistry, with workflow and sample quantity requirements similar to those for our TaqMan® Gene Expression and MicroRNA Assays. By obtaining protein expression results on the same analytical platform, TaqMan® Assays enable direct correlation of mRNA and/or miRNA expression to protein expression. Choose from 6 ready-to-use TaqMan® Protein Assays for human stem cell pluripotency proteins, as well as the common human markers Cystatin B and ICAM1.

Make a TaqMan® Protein Assay Using Your Antibody

The TaqMan® Protein Assays Open Kit facilitates the construction of TaqMan® Protein Assays. Build your own TaqMan® Protein Assays to targets of interest from biotinylated antibodies quickly and easily. Assays can be built from an immunogen-purified polyclonal antibody preparation that is split into two pools or from matched antibody pairs suitable for ELISA, typically made up of one polyclonal antibody and 1 monoclonal antibody.

TaqMan® Protein Assay Workflow

Workflow Stage Predesigned TaqMan® Protein Assays TaqMan® Protein Assay Using Your Antibody
Assay PreparationNABuild TaqMan® Protein Assays using antibodies specific for the protein of interest. Attach biotinylated antibodies to streptavidin oligonucleotide ”prox-oligos” to make assay probes.
Cell/Tissue LysisLyse samples (cells or tissues) using a gentle, 1-step procedure in a buffered non-ionic detergent, with no further sample clean up or purification steps required.Lyse samples (cells) using a gentle, 1-step procedure in a buffered non-ionic detergent, with no further sample clean up or purification steps required.
BindingThe assay probes are target-specific antibodies that are conjugated to oligonucleotides through a biotin-streptavidin linkage. Each oligonucleotide in the pair presents a 5′ or 3′ end that is brought into proximity when the antibodies on the assay probes bind to two different epitopes on the target protein.The assay probes binds to 2 different epitopes on the target protein via antibody/protein interactions. This brings the oligonucleotides on the assay probe pair into proximity.
Ligation/InactivationThe substrate for ligase is a bridge structure formed by hybridization of a third oligonucleotide to the oligonucleotide ends of the assay probe pair. This structure forms preferentially when the assay probes are brought into proximity by binding to the target protein.Hybridization of a third oligonucleotide to the oligonucleotide ends of the assay probe pair forms a bridge structure that is ligated using DNA ligase. After the reaction, protease treatment inactivates the ligase.
TaqMan® Fast Real-Time PCRThe ligation product serves as a DNA template in the real-time PCR using a TaqMan® Protein Assay.Amplification and detection of the ligation product by real-time PCR.
Data AnalysisAnalyze TaqMan® Protein Assay data using our free ProteinAssist™ Software package.Analyze TaqMan® Protein Assay data using our free ProteinAssist™ Software package

Life Technologies Publications

Literature Publications

References on Proximity Ligation Assays

  1. Fredriksson S. and Landegren U. et al. (2002). Protein detection using proximity-dependent DNA ligation assays. Nat. Biotechnol. 20:473-477.
  2. Gullberg M., Landegren U., and Fredriksson S. et al., (2004) Cytokine detection by antibody-based proximity ligation. Proc Natl Acad Sci USA. 101(22):8420-4. Epub 2004 May 21.