Fig. 1: Design of the SNAPSwitch localization sensor.
From: A molecular sensor to quantify the localization of proteins, DNA and nanoparticles in cells
SNAPSwitch localization sensor can be used to quantify trafficking of proteins, DNA or nanoparticles to a subcellular compartment. a SNAPSwtich scheme. SNAPSwitch consists of a quencher, fluorophore and clickable group for attachment conjugated to either side of a benzylguanine group. When SNAPSwitch-labelled material reaches a cellular compartment labelled with a SNAP-tag (e.g. early endosome, cytosol or nucleus), the quencher is transferred to the SNAP-tag, breaking the quenching interaction and allowing the sensor to fluoresce. b SNAPSwitch chemical structure. QSY-21 (purple) is conjugated to the side of the benzylguanine substrate (green) that is transferred to the SNAP-tag. The substrate is linked to an azide (orange) for attachment to the particle or protein of interest through a PEG linker. The fluorophore Cy5 (blue) resides on the side of the substrate that remains with the material after interaction with the SNAP-tag. c SNAP-tag can be localized to different areas of the cell to probe trafficking to different cellular compartments. SNAP-tag fused to the transferrin receptor to probe early endosome localization, to transmembrane protein 106b for late endo/lysosomes trafficking, in the cytosol for endosomal escape of material following endocytosis and in the nucleus for transport of nucleic acids following delivery.
