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P2051
Quest Rhod-4™ Calcium Indicator, a New Red Fluorescent for Screening GPCR & Calcium Channel Targets
Presenter Jinfang Liao, ABD Bioquest, Inc.
Additional Authors: Jianjun He, Desuo Yang and Zhenjun Diwu
Calcium flux assays are preferred methods in drug discovery for screening G protein coupled receptors (GPCRs). Red fluorescent dyes are preferably used for minimizing compound auto-fluorescence interference in HTS assays. Although Rhod-2 has been the most popular red fluorescent Ca2+ indicator, its mitochondrial localization and high basal Ca2+ signal in cells have severely limited its cellular applications. Our Quest Rhod-4 AM has been developed to address these limitations of Rhod-2. Rhod-4 AM  exhibits >200 times fluorescence enhancement upon calcium binding, making Quest Rhod-4 AM an ideal indicator for measurement of intracellular calcium especially when the library compounds have strong auto-fluorescence or the applications require GFP. Quest Rhod-4 AM is more than 4 fold brighter than Rhod-2 AM. In contrast to the mitochondrial localization of Rhod-2 AM, Quest Rhod-4 AM is predominantly localized in cytosol. In addition, Quest Rhod-4 AM can be well excited at 488 nm while Rhod-2 has very minimal excitation at 488 nm.