Features & Solutions



One tag, many colors


FAST is a user-friendly, real-time fluorescent reporting system, whose spectral properties can be tuned at will using TFFluorogens displaying various spectral properties.

You are interested in

avoiding wasting time generating new plasmids or new cell lines with fluorescent reporters displaying spectral properties better suited for your new experiments?

Compatible techniques




How can fast help you?

  • FAST is a small purely monomeric protein, of only 14 kDa. Its small size and minimal genetic footprint (375 bp) minimize the risk of perturbation linked to the use of genetic tags.
  • FAST binds non-covalently TFFluorogens, fluorogenic synthetic dyes that are dark in water and fluoresce only when bound to FAST, allowing specific detection of FAST.
  • TFFluorogens come in a variety of colors: TFCoral (λem 600 nm), TFAmber (λem 558 nm), TFLime (λem 540 nm).

Other key features:

  • FAST provide strong fluorescence immediately upon addition of TFFluorogens even in fully anaerobic conditions
  • As TFFluorogen binds FAST non-covalently, labeling is non-permanent and can be easily reversed by washing TFFluorogen away.

  • The level of labeling can be controlled by adjusting the concentrations of TFFluorogens.

recent papers about this application

A small fluorescence-activating and absorption-shifting tag for tunable protein imaging in vivo

Published in Proc. Natl. Acad. Sci. (USA) 113 (3), 497-502 (2016)

In this seminal paper, Pr. A. Gautier and L. Jullien demonstrate that protein fluorescent labeling with FAST is highly dynamic and fully reversible...

…which opens new exciting perspectives for the development of multiplexing imaging protocols based on sequential labeling.

Dynamic multi-color labeling in living cells

Published in Chem. Sci. 8, 5598-5605 (2017)

In this paper, Pr. A. Gautier and L. Jullien report a collection of fluorogens enabling tuning of the fluorescence color of FAST...

…from green-yellow to orange and red. Beyond allowing the multicolor imaging of FAST-tagged proteins in live cells, these fluorogens enable dynamic color switching because of FAST’s reversible labeling. This unprecedented behavior allows for selective detection of FAST-tagged proteins in cells expressing both green and red fluorescent species through two-color cross-correlation, opening up exciting prospects to overcome spectral crowding and push the frontiers of multiplexed imaging.

Improved chemical-genetic fluorescent markers for protein imaging in living cells

Published in Biochemistry 57, 5648-5653 (2018)

In this paper, Pr. A. Gautier uses rational design to modify the FAST binding pocket for improved fluorescence performances...

…with four different fluorogens. The introduction of a single mutation results in improvements in both quantum yield and dissociation constant with nearly all fluorogens tested. Our improved FAST (iFAST) allowed the generation of a tandem iFAST (td-iFAST) that forms green and red fluorescent reporters 1.6-fold and 2-fold brighter than EGFP and mCherry, respectively, while having a comparable size.

Other Applications

Labeling in anaeroby

Detecting protein-protein interactions

Protein & cell labeling

One tag, many colors

Reversible labeling, Silent Tag

A toolkit for sensing

The Twinkle Factory

We are a French biotech company that provides ground breaking fluorescent chemical-genetic tools for labelling and imaging



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