Features & Solutions



Reversible labeling, Silent Tag


FAST is a user-friendly, real-time fluorescent reporting system, which can act as a silent tag by non-permanent labeling with TFFluorogen.

You are interested in

monitoring the efficiency of transgenesis without permanently labeling your transgenic cell line or organism?

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.
  • As TFFluorogen binds FAST non-covalently, labeling is non-permanent and can be easily reversed by washing TFFluorogens away.

Other key features:

  • FAST provide strong fluorescence immediately upon addition of TFFluorogens even in fully anaerobic conditions.

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

  • TFFluorogens come in a variety of colors: TFCoral (λem 600 nm), TFCitrus (λem 560 nm), TFAmber (λem 558 nm), TFLime (λem 540 nm).

recent paper 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 evidence that fluorescent labeling with the FAST tag is highly dynamic and fully reversible...

…which strikingly contrasts with other tagging systems. As a consequence fluorescent tagging can be made transient, enabling for liberation of observation fluorescence channels. The FAST tag remains silent as long as no fluorogen is added to the medium.

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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