R-phycoerythrin (R-PE) is an intensely bright phycobiliprotein isolated from red algae that exhibits extremely bright red-orange fluorescence with high quantum yields. It is excited by laser lines from 488 to 561 nm, with absorbance maxima at 496, 546, and 565 nm and a fluorescence emission peak at 578 nm. R-PE is a large molecule used for fluorescence-based detection, primarily in flow cytometry, microarray assays, ELISAs, and other applications that require high sensitivity but not photostability.

In practical applications, the sensitivity of R-PE conjugates is usually 5 to 10 times greater than those of the corresponding fluorescein conjugates. In addition, R-PE exhibits:

  • Long-wavelength fluorescence emission
  • Large Stokes shifts
  • Quench resistance due to the protein backbone
  • Very high water solubility
  • Homogeneous structure with defined molecular weights

We offer R-PE conjugated to a variety of primary antibodies, secondary antibodies, and streptavidin. In addition, tandem conjugates of phycobiliproteins are available to generate a range of emission signals from a single excitation wavelength.

Phycoerythrin (R-PE) dashboard

Initial brightness

Phycoerythrin, also known as R-PE, is typically used for flow cytometry, microarrays, ELISA, and other applications that require high sensitivity but not photostability.  

Photostability in buffer


  158 488–561 TRITC 565 578  
Stain index

Laser line

Common filter set

Excitation max

Emission max

R-phycoerythrin (R-PE) products

We offer a broad range of RPE products, including primary antibodies, secondary antibodies, streptavidin conjugates, and more.

Flow cytometry histogram showing human mononuclear cells stained with anti-CD4 complexed with Invitrogen R‑phycoerythrin Zenon labeling reagent.



Molecular Probes Handbook

The significantly revised 11th Edition is the most complete fluorescence labeling and detection reference available. The Molecular Probes Handbook can help you achieve the best experimental results for your fluorescence labeling and detection experiments. View the handbook online or order your own copy.

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Flow cytometry instrument controls and standards

Keep your flow cytometry running at peak efficiency with instrument set-up, calibration, and counting beads including alignment and linearity beads, compensation tools, and cell-counting beads.

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Cell stain tool

Stain your own cell by using our simulation tool to develop reproducible results with many of our signature fluorescent dyes. Develop your multiplexing strategy for antibody probes, reactive dyes, and counterstains to create your perfectly labeled fluorescent cell.

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Fluorescence SpectraViewer

Plot and compare spectra and check the spectral compatibility for common fluorophores including all of the fluorescent probes from Thermo Fisher Scientific. The Fluorescence SpectraViewer tool is formatted for both microscope imaging and flow cytometry applications.

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