FLII¹²Pglu-700μδ6 is a FRET glucose sensor that can detect changes in glucose concentration in a millimolar range. It contains a glucose-binding domain from the Escherichia coli MglB gene, into which ECFP has been inserted, fused to Citrine via a linker sequence. Glucose binding elicits a conformational change, which can be detected by fluorescence resonance energy transfer (FRET) between the ECFP and Citrine fluorophores (PMID:18177733).