We present a novel method, termed competitive fluorescent ligand assay for inositol 1,4,5-trisphosphate (CFLA-IP3), to measure inositol 1,4,5-trisphosphate (IP3). This method is based on fluorescence resonance energy transfer (FRET) between two fluorescent molecules, a fluorescent IP3-binding protein and its fluorescent ligand. Binding of these fluorescent molecules generates a FRET signal, and the IP3-dependent decrease in the FRET signal due to displacement of the fluorescent ligand is detected by fluorescence microscopy.
Inositol 1,4,5-trisphosphate IP3 receptor Ligand binding domain Fluorescent ligand Fluorescence resonance energy transfer Fluorescence microscopy
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This study was partly supported by the MEXT/Japan Society for the Promotion of Sciences (JSPS) KAKENHI under Grant No. JP16H01433 “Resonance Bio” and Grant No. 26670812 (to A.T.).
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