Related Experiment Video
Updated: Aug 19, 2026

Multi-photon Intracellular Sodium Imaging Combined with UV-mediated Focal Uncaging of Glutamate in CA1 Pyramidal Neurons
Published on: October 8, 2014
Inactivation of a quisqualate-sensitive glutamate receptor by photosensitive analogues of philanthotoxin
R A Goodnow1, K Nakanishi, H L Sudan
1Department of Chemistry, Columbia University, New York, NY.
Abstract:
Three photosensitive, synthetic analogues of delta-philanthotoxin (PhTX-433) have been tested on the locust, excitatory nerve-muscle system. At 10(-9) M they inhibit reversibly the postjunctional currents (EPSCs) recorded from muscle fibres during motor nerve stimulation, mainly by non-competitively antagonizing postjunctional quisqualate-sensitive glutamate receptors (Quis-R), probably through open channel block. This use-dependent antagonism is characteristic of the philanthotoxins. When the preparation was irradiated with 270 nm U.V. during toxin application and nerve stimulation the EPSCs were inhibited irreversibly. Irradiation of the preparation alone or in the presence of philanthotoxins (e.g. PhTX-433) which are not photosensitive did not lead to irreversible inhibition of the EPSC. It is concluded that the three photosensitive toxins bind covalently to Quis-R in its open channel conformation during U.V. irradiation, thereby irreversibly blocking the channel gated by this receptor.
Related Concept Videos
Channel Rhodopsins
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
Ligand-Gated Ion Channel Receptor: Gating Mechanism
Photoreceptors and Visual Pathways
Botulism

