Figure 7.

The main architectural types of genetically encoded fluorescent indicators (GEFIs) of metabolic and redox parameters based on a single optical reporter. Redox-sensitive fluorescent proteins (roFPs) with (A) or without (B) additional sensory domain. (C) Indicators based on a circularly permuted fluorescent protein (cpFP) with a sensory domain that can be modified by analyte. (D) Indicators based on the direct effect of a sensory domain-bound analyte on the chromophore of the FP. (E) Indicators based on the ligand binding by a sensory domain which transmits conformational changes to the chromophore microenvironment altering its optical properties.