Figure 1.

General design and operation of a FP-based biosensor. (A) Molecular toolbox for the generation of modular FP-based biosensors. A sensing unit comprised of an intrinsic or engineered molecular switch is combined with a FP-based reporting unit. Optionally, a targeting motif can be added. (B) Schematic example of the operation of a unimolecular FRET-based PTM sensor with an engineered molecular switch. The substrate peptide is modified resulting in a conformational change that increases FRET. (C) Representative schematic diagram of the dependence of the readout on the PTM activity or state, respectively, for a FP-based PTM reporter, also illustrating the general properties of a biosensor.