G protein modulation of recombinant P/Q-type calcium channels by regulators of G protein signalling proteins.
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.
Mark
M D
MD
Department of Physiology II, University of Tuebingen, Ob dem Himmelreich 7, 72074 Tuebingen, Germany.
Wittemann
S
S
Herlitze
S
S
D001464:Barium / Q000494:pharmacology; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism; D020864:Calcium Channels, N-Type; D020865:Calcium Channels, P-Type / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D020907:Calcium Channels, Q-Type / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D019204:GTP-Binding Proteins / Q000378:metabolism* / Q000494:pharmacology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010750:Phosphoproteins / Q000096:biosynthesis; D021122:Protein Subunits; D020710:RGS Proteins / Q000378:metabolism* / Q000494:pharmacology; D011930:Reaction Time / Q000187:drug effects; D043585:Receptor, Muscarinic M2; D011976:Receptors, Muscarinic / Q000378:metabolism; D011994:Recombinant Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
D001464:Barium; D015220:Calcium Channels; D020864:Calcium Channels, N-Type; D020865:Calcium Channels, P-Type; D020907:Calcium Channels, Q-Type; D019204:GTP-Binding Proteins; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D021122:Protein Subunits; D020710:RGS Proteins; D043585:Receptor, Muscarinic M2; D011976:Receptors, Muscarinic; D011994:Recombinant Proteins; C105656:CACNA1A protein, human; C105345:Rgs2 protein, mouse; C097187:regulator of G-protein signalling 19; C098799:RGS4 protein