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Voltage-dependent regulation of Ca(V)2.2 channels by G(q)-coupled receptor is facilitated by membrane-localized beta subunit

Voltage-dependent regulation of Ca(V)2.2 channels by G(q)-coupled receptor is facilitated by membrane-localized beta subunit
Keum, DongilBaek, ChristinaKim, Dong-IlKweon, Hae-JinSuh, Byung-Chang
DGIST Authors
Suh, Byung-Chang
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CACNA1B Protein, HumanCalcium Channels, N-TypeCell LineChemistryFluorescence Resonance Energy TransferG Protein-Coupled ReceptorGenetic TransfectionHumanHumansMetabolismMuscarinic M1 ReceptorPatch-Clamp TechniquePatch-Clamp TechniquesPhosphatidylinositol 4,5-DiphosphatePhosphatidylinositol 4,5 BisphosphatePhysiologyReceptor, Muscarinic M1Receptors, G-Protein-CoupledSignal TransductionTransfection
G protein-coupled receptors (GPCRs) signal through molecular messengers, such as Gβγ, Ca2+, and phosphatidylinositol 4,5-bisphosphate (PIP2), to modulate N-type voltage-gated Ca2+ (CaV2.2) channels, playing a crucial role in regulating synaptic transmission. However, the cellular pathways through which GqPCRs inhibit CaV2.2 channel current are not completely understood. Here, we report that the location of CaV β subunits is key to determining the voltage dependence of CaV2.2 channel modulation by GqPCRs. Application of the muscarinic agonist oxotremorine-M to tsA-201 cells expressing M1 receptors, together with CaV N-type α1B, α2δ1, and membrane-localized β2a subunits, shifted the currentvoltage relationship for CaV2.2 activation 5 mV to the right and slowed current activation. Muscarinic suppression of CaV2.2 activity was relieved by strong depolarizing prepulses. Moreover, when the C terminus of β-adrenergic receptor kinase (which binds Gβγ) was coexpressed with N-type channels, inhibition of CaV2.2 current after M1 receptor activation was markedly reduced and delayed, whereas the delay between PIP2 hydrolysis and inhibition of CaV2.2 current was decreased. When the Gβγ-insensitive CaV2.2 α1C-1B chimera was expressed, voltage-dependent inhibition of calcium current was virtually abolished, suggesting that M1 receptors act through Gβγ to inhibit CaV2.2 channels bearing membrane-localized CaV β2a subunits. Expression of cytosolic β subunits such as β2b and β3, as well as the palmitoylationnegative mutant β2a(C3,4S), reduced the voltage dependence of M1 muscarinic inhibition of CaV2.2 channels, whereas it increased inhibition mediated by PIP2 depletion. Together, our results indicate that, with membrane-localized CaV β subunits, CaV2.2 channels are subject to Gβγ-mediated voltage-dependent inhibition, whereas cytosol-localized β subunits confer more effective PIP2-mediated voltage-independent regulation. Thus, the voltage dependence of GqPCR regulation of calcium channels can be determined by the location of isotype-specific CaV β subunits. © 2014 Keum et al.
Related Researcher
  • 서병창 Suh, Byung-Chang 뇌과학과
  • Research Interests Molecular mechanisms of epilepsy and sensory pain transmission; Signaling mechanism of ion channel regulation and membrane excitability; 분자전기생리; 간질 및 통증의 분자적 기전 연구
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Department of Brain Sciences Laboratory of Brain Signal and Synapse Research 1. Journal Articles


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