Observation of calcium ion concentration dynamics with HeLa cells expressing Yellow Cameleon 3.60 with 457nm laser excitation prior ATP stimulation

Equipment: A1R⁺si Confocal

Method: Emission of CFP and YFP is scanned in ratio view where red and purple in color scale correspond to high and low FRET efficiency, respectively. Along with the increase of calcium ion concentration in the cell, the intermolecular FRET efficiency between CFP and YFP within Yellow Cameleon 3.60 increases, i.e. the CFP fluorescence intensity decreases, and the YFP fluorescence intensity increases.