An endoplasmic reticulum-targeting fluorescent probe for discriminatory detection of Cys, Hcy and GSH in living cells.

Endoplasmic reticulum, known to us as the ER, is the largest organelle in many kinds of eukaryotic cells and plays vital roles in maintaining the normal function of cells. Biothiols (Cys, Hcy, GSH) in secretory proteins will be modified as they enter the ER and are of great importance in balancing redox state of ER environments. In this article, we have developed the first endoplasmic reticulum-targeting fluorescent probe, ER-CP, for concurrent distinguishment of Cys, Hcy and GSH with favorable sensitivity and selectivity. ER-CP was successfully used in fluorescence imaging of Cys, Hcy and GSH in HeLa cells. In addition, ER-CP exhibited a good ER-targeting property (Pearson's correlation coefficient = 0.90).