Fig. 5.

SMIT1 plus myo-inositol enhances IP₃ production and calcium release from intracellular stores. (A) Diagram of IP₃ detection by FRET of the LIBRAvIII probe, which has a FRET pair flanking an IP₃ binding domain from the rat IP₃ receptor. (B) Representative control time course of the photometric FRET ratio change of LIBRAvIII induced by IP₃ generation after application of Oxo-M. (C) Same as B after SMIT1/myo-inositol treatment. (D) Negative control using an IP₃-insensitive LIBRA version N. The FRET ratio of LIBRAvN showed more fluctuations but was not responsive to Oxo-M. (E) Summary of time constants (τ) of the recoveries of LIBRA FRET ratios for experiments as in B and C (n = 5). (F) The effects of SMIT1/myo-inositol on the increase of intracellular calcium concentration after applying Oxo-M. The orange trace illustrates an example with Ca²⁺ oscillation in the same condition as the red trace. (G) Summary of Ca²⁺ release elicited by Oxo-M as in F; bars show the integral of the Ca²⁺ rise (n = 5–6). Means ± SEM, *P < 0.05.