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Identification of a new type of prepulse facilitation in honey bee CaV4 Ca2+ channel
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International audience. We have recently identified a honeybee homologue of DSC1, the Drosophila channel 1 displaying sequence similarity to the voltage‐gated sodium channel (NaV), identified over twenty years ago. This channel exhibits strict selectivity for Ca2+, an unprecedented type of inactivation, which depends on both an IFM motif, like NaV, and on the permeating divalent cation, like CaV1.2, and defines a new family of Ca2+ channels, called CaV4. We show that CaV4 exhibits a prepulse‐dependent current facilitation that develops during depolarisations of small amplitudes. Increasing the duration of the depolarisations decreases current facilitation. Analysis at the single channel level demonstrate that neither the single current amplitude nor the mean channel open‐time, the short closed‐time or the number of opening per burst are affected. This current–dependent facilitation is primarily due to an increase in the open probability at ‐20 mV. Our study underscores the unique profile of the CaV4 Ca2+ channel and defines this channel as a novel class of voltage‐gated Ca2+ channel.
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