Abstract
1. Fast synaptic transmission is triggered by the activation of presynaptic Ca2+ channels which can be inhibited by Gbetagamma subunits via G protein-coupled receptors (GPCR). Regulators of G protein signalling (RGS) proteins are GTPase-accelerating proteins (GAPs), which are responsible for >100-fold increases in the GTPase activity of G proteins and might be involved in the regulation of presynaptic Ca2+ channels. In this study we investigated the effects of RGS2 on G protein modulation of recombinant P/Q-type channels expressed in a human embryonic kidney (HEK293) cell line using whole-cell recordings. 2. RGS2 markedly accelerates transmitter-mediated inhibition and recovery from inhibition of Ba2+ currents (IBa) through P/Q-type channels heterologously expressed with the muscarinic acetylcholine receptor M2 (mAChR M2). 3. Both RGS2 and RGS4 modulate the prepulse facilitation properties of P/Q-type Ca2+ channels. G protein reinhibition is accelerated, while release from inhibition is slowed. These kinetics depend on the availability of G protein alpha and betagamma subunits which is altered by RGS proteins. 4. RGS proteins unmask the Ca2+ channel beta subunit modulation of Ca2+ channel G protein inhibition. In the presence of RGS2, P/Q-type channels containing the beta2a and beta3 subunits reveal significantly altered kinetics of G protein modulation and increased facilitation compared to Ca2+ channels coexpressed with the beta1b or beta4 subunit.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Barium / pharmacology
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Calcium Channels / genetics
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Calcium Channels / metabolism
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Calcium Channels, N-Type
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Calcium Channels, P-Type / drug effects
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Calcium Channels, P-Type / genetics
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Calcium Channels, P-Type / metabolism*
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Calcium Channels, Q-Type / drug effects
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Calcium Channels, Q-Type / genetics
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Calcium Channels, Q-Type / metabolism*
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Cell Line
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GTP-Binding Proteins / metabolism*
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GTP-Binding Proteins / pharmacology
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Guanosine 5'-O-(3-Thiotriphosphate) / pharmacology
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Humans
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Ion Channel Gating / drug effects
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Kidney / cytology
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Kidney / metabolism*
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Nerve Tissue Proteins / genetics
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Nerve Tissue Proteins / metabolism
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Patch-Clamp Techniques
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Phosphoproteins / biosynthesis
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Protein Subunits
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RGS Proteins / metabolism*
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RGS Proteins / pharmacology
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Reaction Time / drug effects
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Receptor, Muscarinic M2
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Receptors, Muscarinic / metabolism
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Recombinant Proteins / drug effects
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Signal Transduction / drug effects
Substances
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CACNA1A protein, human
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Calcium Channels
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Calcium Channels, N-Type
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Calcium Channels, P-Type
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Calcium Channels, Q-Type
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Nerve Tissue Proteins
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Phosphoproteins
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Protein Subunits
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RGS Proteins
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Receptor, Muscarinic M2
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Receptors, Muscarinic
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Recombinant Proteins
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Rgs2 protein, mouse
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regulator of G-protein signalling 19
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voltage-dependent calcium channel (P-Q type)
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RGS4 protein
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Barium
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Guanosine 5'-O-(3-Thiotriphosphate)
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GTP-Binding Proteins