C-geNOps are cyan fluorescent probe for single cell NO• measurements
C-geNOps are a class of cyan fluorescent genetically encoded sensor capable for specific detection of intracellular nitric oxide (NO•) dynamics either within the cytosol (C-geNOp) or mitochondria (mtC-geNOp). These constructs have been developed on the basis of cyan fluorescent protein (CFP) that is conjugated with a NO•-binding domain of the Escherichia coli protein NorR. Upon NO• binding to functional C-geNOps the cyan fluorescence intensity is immediately quenched. The NO•-dependent quenching effect correlates with the cellular NO• concentration. Fluorescence of C-geNOps rapidly and fully recovers in the absence of NO•. Hence, C-geNOps provide a highly specific real-time read-out of local NO• dynamics on the level of individual cells or organelles (mitochondria). The excitation and emission maxima of C-geNOps are at 430 nm and 480 nm, respectively. Standard optical filters optimized for imaging of CFP should be used. ΔC-geNOps are NO insensitive constructs that should be used as respective controls.