Protocol for synthesis and use of a turn-on fluorescent probe for quantifying labile Zn 2+ in the Golgi apparatus in live cells.

Quantitative analysis using a turn-on fluorescent probe is inherently difficult due to the dependency of the fluorescence intensity on the probe concentration. To overcome this limitation, we developed an in situ quantification method using a turn-on fluorescent probe and a standard fluorophore, which are colocalized by protein tag technology. This protocol describes the synthesis of a Zn probe, named , and the procedure to quantify the labile Zn concentration in the Golgi of live HeLa cells by confocal fluorescence microscopy. For complete details on the use and execution of this protocol, please refer to Kowada et al. (2020).