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Updated: Jun 13, 2025

Determination of the Relative Cell Surface and Total Expression of Recombinant Ion Channels Using Flow Cytometry
Published on: September 28, 2016
Voltage-dependent G-protein regulation of CaV2.2 (N-type) channels
Michelle Nilsson1, Kaiqian Wang1, Teresa Mínguez-Viñas1
1Division of Cell and Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, SE-581 85 Linköping, Sweden.
Abstract:
How G proteins inhibit N-type, voltage-gated, calcium-selective channels (CaV2.2) during presynaptic inhibition is a decades-old question. G proteins Gβγ bind to intracellular CaV2.2 regions, but the inhibition is voltage dependent. Using the hybrid electrophysiological and optical approach voltage-clamp fluorometry, we show that Gβγ acts by selectively inhibiting a subset of the four different CaV2.2 voltage-sensor domains (VSDs I to IV). During regular "willing" gating, VSD-I and -IV activations resemble pore opening, VSD III activation is hyperpolarized, and VSD II appears unresponsive to depolarization. In the presence of Gβγ, CaV2.2 gating is "reluctant": pore opening and VSD I activation are strongly and proportionally inhibited, VSD IV is modestly inhibited, while VSD III is not. We propose that Gβγ inhibition of VSDs I and IV underlies reluctant CaV2.2 gating and subsequent presynaptic inhibition.
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