Abstract
Spectrofluorimetric measurements were conducted to quantify, in real-time, membrane permeability changes resulting from the treatment of Sf9 insect cells (Spodoptera frugiperda, Lepidoptera) with different Bacillus thuringiensis Cry insecticidal proteins. Coumarin-derived CD222 and Merocyanin-540 probes were respectively used to monitor extracellular K+ and membrane potential variations upon Sf9 cells incubation with Cry toxins. Our results establish that Cry1C induces, after a delay, the depolarization of the cell membrane and the full depletion of intracellular K+. These changes were not observed upon Sf9 cells treated with Cry1A family toxins. Both the rate of the K+ efflux and the delay before its onset were dependent on toxin concentration. Both parameters were sensitive to temperature but only the delay was affected by pH. Cry1C-induced K+ efflux was inhibited by lanthanum ions in a dose-dependent manner. This study provides the first kinetic and quantitative characterization of the ion fluxes through the channels formed by a Cry toxin in the plasma membrane of a susceptible insect cell line.
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Received: 4 October 1999/Revised: 21 December 1999
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Guihard, G., Vachon, V., Laprade, R. et al. Kinetic Properties of the Channels Formed by the Bacillus thuringiensis Insecticidal Crystal Protein Cry1C in the Plasma Membrane of Sf9 Cells. J. Membrane Biol. 175, 115–122 (2000). https://doi.org/10.1007/s002320001060
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DOI: https://doi.org/10.1007/s002320001060