Photo-Activatable Probes for the Analysis of Receptor Function in Living Cells

Photo-activatable (caged) probes are powerful research tools for biological investigation. The superb maneuverability of a light beam allows researchers to activate caged probes with pinpoint accuracy. Recent developments in caging chemistry and two-photon excitation technique further enhance our capability to perform photo-uncaging with even higher spatial and temporal resolution, offering new photonic approaches to study cell signaling dynamics in greater detail. Here we present a sample method that combines the techniques of photo-activation and digital fluorescence microscopy to assay an important class of intracellular receptors for the second messenger D-myo -inositol 1,4,5-trisphosphate (Ins(1,4,5)P₃ , or IP₃ ). The imaging assay is performed in fully intact living cells using a caged and cell membrane permeable ester derivative of IP₃ , cm-IP₃ /PM.