Spatiotemporal Laser Inactivation of Inositol 1,4,5-Trisphosphate Receptors Using Synthetic Small-Molecule Probes Original Research Article

A malachite green-conjugated inositol 1,4,5-trisphosphate (MGIP3) induces specific inactivation of IP3 receptor (IP3R) in tissue samples upon laser irradiation. To verify potential usefulness of the method for studies of cellular Ca2+ signaling, we conducted laser inactivation at the single-cell level and show that IP3R was inactivated with extremely high spatiotemporal resolution. In the presence of MGIP3, the Ca2+ release function of IP3R in single B lymphoma cells decayed exponentially with increasing duration of laser irradiation with a time constant of 3.4 s. Moreover, by confining laser irradiation to a spatially distinct region of differentiated PC12 cells, subcellular inactivation of IP3R was attained, as revealed by a loss of local Ca2+ signal. Such real-time inactivation of IP3R only within a subcellular region may provide a powerful method for investigating spatiotemporal dynamics of Ca2+ signaling.