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Updated: Sep 21, 2026

Single-molecule Super-resolution Imaging of Phosphatidylinositol 4,5-bisphosphate in the Plasma Membrane with Novel Fluorescent Probes
Published on: October 15, 2016
Li(+)-induced structural changes of synaptic ribbons are related to the phosphoinositide metabolism in photoreceptor
1Institute of Anatomy, Julius-Maximilians-University Würzburg, FRG.
Abstract:
Synaptic ribbons are specialized cytoskeletal components of the presynaptic exocytotic machinery in photoreceptors. In cone photoreceptors, these structures are highly dynamic disappearing during darkness and reforming in the light phase. In this study we wanted to characterize the second messengers involved in the regulation of these cyclic changes. We show that synaptic ribbons in cone photoreceptors are very sensitive to both Li+ and inositol 1,4,5-trisphosphate suggesting that inositol polyphosphates might play a physiological role in the disassembly of synaptic ribbons. The presence of the phosphoinositide pathway was demonstrated in isolated photoreceptor synapses. The phosphoinositide metabolism in photoreceptor synapses was dark-activated and correlated with the disappearance of synaptic ribbons during dark-adaptation. Since Li+ and inositol 1,4,5-trisphosphate only influenced synaptic ribbons in cones but not in rods the dark-activated phosphoinositide metabolism should be largely ascribed to cone synapses.
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