Chen, Y. et al. Angew. Chem. Int. Ed. Engl. 57, 12390–12394 (2018).
Numerous strategies exist for tagging proteins of interest for downstream applications such as fluorescence microscopy and spectroscopy. However, smaller, brighter, and more photostable probes are still needed. Chen et al. have developed a green fluorescent probe for protein labeling that is fluorogenic, meaning it turns on only when bound to its target. Their probe has two components: a peptide tag containing two cysteine residues that is used to tag the target protein, and a BODIPY-based dye conjugated to two maleimide groups. When free in solution, the dye is nonfluorescent. However, when both maleimide groups react with the cysteines on the peptide tag, the dye turns on. The researchers demonstrate that their labeling approach works in both bacterial lysates and living mammalian cells.