scholarly journals Molecular moieties masking Ca2+-dependent facilitation of voltage-gated Cav2.2 Ca2+ channels

2017 ◽  
Vol 150 (1) ◽  
pp. 83-94 ◽  
Author(s):  
Jessica R. Thomas ◽  
Jussara Hagen ◽  
Daniel Soh ◽  
Amy Lee
Keyword(s):  
Functional Divergence ◽  
Short Term ◽  
Voltage Gated ◽  
Regulatory Domains ◽  
Dependent Inactivation ◽  
Weak Binding ◽  
Ef Hand ◽  
Molecular Determinants ◽  
Ca2 Channels ◽  
Α1 Subunit

Voltage-gated Cav2.1 (P/Q-type) Ca2+ channels undergo Ca2+-dependent inactivation (CDI) and facilitation (CDF), both of which contribute to short-term synaptic plasticity. Both CDI and CDF are mediated by calmodulin (CaM) binding to sites in the C-terminal domain of the Cav2.1 α1 subunit, most notably to a consensus CaM-binding IQ-like (IQ) domain. Closely related Cav2.2 (N-type) channels display CDI but not CDF, despite overall conservation of the IQ and additional sites (pre-IQ, EF-hand–like [EF] domain, and CaM-binding domain) that regulate CDF of Cav2.1. Here we investigate the molecular determinants that prevent Cav2.2 channels from undergoing CDF. Although alternative splicing of C-terminal exons regulates CDF of Cav2.1, the splicing of analogous exons in Cav2.2 does not reveal CDF. Transfer of sequences encoding the Cav2.1 EF, pre-IQ, and IQ together (EF-pre-IQ-IQ), but not individually, are sufficient to support CDF in chimeric Cav2.2 channels; Cav2.1 chimeras containing the corresponding domains of Cav2.2, either alone or together, fail to undergo CDF. In contrast to the weak binding of CaM to just the pre-IQ and IQ of Cav2.2, CaM binds to the EF-pre-IQ-IQ of Cav2.2 as well as to the corresponding domains of Cav2.1. Therefore, the lack of CDF in Cav2.2 likely arises from an inability of its EF-pre-IQ-IQ to transduce the effects of CaM rather than weak binding to CaM per se. Our results reveal a functional divergence in the CDF regulatory domains of Cav2 channels, which may help to diversify the modes by which Cav2.1 and Cav2.2 can modify synaptic transmission.

scholarly journals Voltage-gated calcium channels in GtoPdb v.2021.2

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
William A. Catterall ◽  
Edward Perez-Reyes ◽  
Terrance P. Snutch ◽  
Jörg Striessnig
Keyword(s):  
High Voltage ◽  
Low Voltage ◽  
Transmembrane Domains ◽  
Voltage Gated ◽  
Voltage Dependent ◽  
Alternatively Spliced ◽  
Membrane Spanning ◽  
Voltage Gated Ion Channels ◽  
Ca2 Channels ◽  
Α1 Subunit

Calcium (Ca2+) channels are voltage-gated ion channels present in the membrane of most excitable cells. The nomenclature for Ca2+channels was proposed by [127] and approved by the NC-IUPHAR Subcommittee on Ca2+ channels [70]. Most Ca2+ channels form hetero-oligomeric complexes. The α1 subunit is pore-forming and provides the binding site(s) for practically all agonists and antagonists. The 10 cloned α1-subunits can be grouped into three families: (1) the high-voltage activated dihydropyridine-sensitive (L-type, CaV1.x) channels; (2) the high- to moderate-voltage activated dihydropyridine-insensitive (CaV2.x) channels and (3) the low-voltage-activated (T-type, CaV3.x) channels. Each α1 subunit has four homologous repeats (I-IV), each repeat having six transmembrane domains and a pore-forming region between transmembrane domains S5 and S6. Voltage-dependent gating is driven by the membrane spanning S4 segment, which contains highly conserved positive charges that respond to changes in membrane potential. All of the α1-subunit genes give rise to alternatively spliced products. At least for high-voltage activated channels, it is likely that native channels comprise co-assemblies of α1, β and α2-δ subunits. The γ subunits have not been proven to associate with channels other than the α1s skeletal muscle Cav1.1 channel. The α2-δ1 and α2-δ2 subunits bind gabapentin and pregabalin.

Voltage- and calcium-dependent inactivation in high voltage-gated Ca2+ channels

2006 ◽  
Vol 90 (1-3) ◽  
pp. 104-117 ◽  
Author(s):  
T CENS ◽  
M ROUSSET ◽  
J LEYRIS ◽  
P FESQUET ◽  
P CHARNET
Keyword(s):  
High Voltage ◽  
Voltage Gated ◽  
Calcium Dependent ◽  
Dependent Inactivation ◽  
Ca2 Channels

scholarly journals Critical Determinants of Ca2+-Dependent Inactivation within an EF-Hand Motif of L-Type Ca2+ Channels

2000 ◽  
Vol 78 (4) ◽  
pp. 1906-1920 ◽  
Author(s):  
Blaise Z. Peterson ◽  
Joanna S. Lee ◽  
Jennifer G. Mulle ◽  
Yan Wang ◽  
Marita de Leon ◽  
...  
Keyword(s):  
Dependent Inactivation ◽  
Ef Hand ◽  
Ca2 Channels

scholarly journals Voltage-gated calcium channels (CaV) in GtoPdb v.2021.3

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
William A. Catterall ◽  
Edward Perez-Reyes ◽  
Terrance P. Snutch ◽  
Jörg Striessnig
Keyword(s):  
High Voltage ◽  
Low Voltage ◽  
Excitable Cells ◽  
Voltage Gated ◽  
Voltage Dependent ◽  
Alternatively Spliced ◽  
Membrane Spanning ◽  
Voltage Gated Ion Channels ◽  
Ca2 Channels ◽  
Α1 Subunit

Ca2+ channels are voltage-gated ion channels present in the membrane of most excitable cells. The nomenclature for Ca2+channels was proposed by [127] and approved by the NC-IUPHAR Subcommittee on Ca2+ channels [70]. Most Ca2+ channels form hetero-oligomeric complexes. The α1 subunit is pore-forming and provides the binding site(s) for practically all agonists and antagonists. The 10 cloned α1-subunits can be grouped into three families: (1) the high-voltage activated dihydropyridine-sensitive (L-type, CaV1.x) channels; (2) the high- to moderate-voltage activated dihydropyridine-insensitive (CaV2.x) channels and (3) the low-voltage-activated (T-type, CaV3.x) channels. Each α1 subunit has four homologous repeats (I-IV), each repeat having six transmembrane domains (S1-S6) and a pore-forming region between S5 and S6. Voltage-dependent gating is driven by the membrane spanning S4 segment, which contains highly conserved positive charges that respond to changes in membrane potential. All of the α1-subunit genes give rise to alternatively spliced products. At least for high-voltage activated channels, it is likely that native channels comprise co-assemblies of α1, β and α2-δ subunits. The γ subunits have not been proven to associate with channels other than the α1s skeletal muscle Cav1.1 channel. The α2-δ1 and α2-δ2 subunits bind gabapentin and pregabalin.

scholarly journals Activity-dependent regulation of T-type calcium channels by submembrane calcium ions

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Magali Cazade ◽  
Isabelle Bidaud ◽  
Philippe Lory ◽  
Jean Chemin
Keyword(s):  
Calcium Ions ◽  
Large Decrease ◽  
Channel Activity ◽  
Ionotropic Receptors ◽  
Voltage Gated ◽  
Dependent Inactivation ◽  
Steady State Inactivation ◽  
Activity Dependent ◽  
Hyperpolarizing Shift ◽  
Ca2 Channels

Voltage-gated Ca2+ channels are involved in numerous physiological functions and various mechanisms finely tune their activity, including the Ca2+ ion itself. This is well exemplified by the Ca2+-dependent inactivation of L-type Ca2+ channels, whose alteration contributes to the dramatic disease Timothy Syndrome. For T-type Ca2+ channels, a long-held view is that they are not regulated by intracellular Ca2+. Here we challenge this notion by using dedicated electrophysiological protocols on both native and expressed T-type Ca2+ channels. We demonstrate that a rise in submembrane Ca2+ induces a large decrease in T-type current amplitude due to a hyperpolarizing shift in the steady-state inactivation. Activation of most representative Ca2+-permeable ionotropic receptors similarly regulate T-type current properties. Altogether, our data clearly establish that Ca2+ entry exerts a feedback control on T-type channel activity, by modulating the channel availability, a mechanism that critically links cellular properties of T-type Ca2+ channels to their physiological roles.

scholarly journals Voltage-gated calcium channels (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

2019 ◽  
Vol 2019 (4) ◽  
Author(s):  
William A. Catterall ◽  
Edward Perez-Reyes ◽  
Terrance P. Snutch ◽  
Jörg Striessnig
Keyword(s):  
High Voltage ◽  
Low Voltage ◽  
Transmembrane Domains ◽  
Excitable Cells ◽  
Voltage Gated ◽  
Alternatively Spliced ◽  
Membrane Spanning ◽  
Voltage Gated Ion Channels ◽  
Ca2 Channels ◽  
Α1 Subunit

Calcium (Ca2+) channels are voltage-gated ion channels present in the membrane of most excitable cells. The nomenclature for Ca2+channels was proposed by [110] and approved by the NC-IUPHAR Subcommittee on Ca2+ channels [60]. Ca2+ channels form hetero-oligomeric complexes. The α1 subunit is pore-forming and provides the binding site(s) for practically all agonists and antagonists. The 10 cloned α1-subunits can be grouped into three families: (1) the high-voltage activated dihydropyridine-sensitive (L-type, CaV1.x) channels; (2) the high-voltage activated dihydropyridine-insensitive (CaV2.x) channels and (3) the low-voltage-activated (T-type, CaV3.x) channels. Each α1 subunit has four homologous repeats (I–IV), each repeat having six transmembrane domains and a pore-forming region between transmembrane domains S5 and S6. Gating is thought to be associated with the membrane-spanning S4 segment, which contains highly conserved positive charges. Many of the α1-subunit genes give rise to alternatively spliced products. At least for high-voltage activated channels, it is likely that native channels comprise co-assemblies of α1, β and α2–δ subunits. The γ subunits have not been proven to associate with channels other than the α1s skeletal muscle Cav1.1 channel. The α2–δ1 and α2–δ2 subunits bind gabapentin and pregabalin.

scholarly journals Voltage-gated calcium channels (version 2020.5) in the IUPHAR/BPS Guide to Pharmacology Database

2020 ◽  
Vol 2020 (5) ◽  
Author(s):  
William A. Catterall ◽  
Edward Perez-Reyes ◽  
Terrance P. Snutch ◽  
Jörg Striessnig
Keyword(s):  
High Voltage ◽  
Low Voltage ◽  
Transmembrane Domains ◽  
Voltage Gated ◽  
Voltage Dependent ◽  
Alternatively Spliced ◽  
Membrane Spanning ◽  
Voltage Gated Ion Channels ◽  
Ca2 Channels ◽  
Α1 Subunit

Calcium (Ca2+) channels are voltage-gated ion channels present in the membrane of most excitable cells. The nomenclature for Ca2+channels was proposed by [120] and approved by the NC-IUPHAR Subcommittee on Ca2+ channels [68]. Ca2+ channels form hetero-oligomeric complexes. The α1 subunit is pore-forming and provides the binding site(s) for practically all agonists and antagonists. The 10 cloned α1-subunits can be grouped into three families: (1) the high-voltage activated dihydropyridine-sensitive (L-type, CaV1.x) channels; (2) the high-voltage activated dihydropyridine-insensitive (CaV2.x) channels and (3) the low-voltage-activated (T-type, CaV3.x) channels. Each α1 subunit has four homologous repeats (I-IV), each repeat having six transmembrane domains and a pore-forming region between transmembrane domains S5 and S6. Voltage-dependent gating is driven by the membrane spanning S4 segment, which contains highly conserved positive charges that respond to changes in membrane potential. Many of the α1-subunit genes give rise to alternatively spliced products. At least for high-voltage activated channels, it is likely that native channels comprise co-assemblies of α1, β and α2-δ subunits. The γ subunits have not been proven to associate with channels other than the α1s skeletal muscle Cav1.1 channel. The α2-δ1 and α2-δ2 subunits bind gabapentin and pregabalin.

scholarly journals Functional Architecture of the Inner Pore of a Voltage-gated Ca2+ Channel

2005 ◽  
Vol 126 (3) ◽  
pp. 193-204 ◽  
Author(s):  
Xiao-guang Zhen ◽  
Cheng Xie ◽  
Aileen Fitzmaurice ◽  
Carl E. Schoonover ◽  
Eleza T. Orenstein ◽  
...  
Keyword(s):  
Drug Binding ◽  
Ion Permeation ◽  
K Channels ◽  
Voltage Gated ◽  
Transmembrane Segments ◽  
Substituted Cysteine Accessibility ◽  
Loose Packing ◽  
Ca2 Channels ◽  
Α1 Subunit ◽  
Inner Pore

The inner pore of voltage-gated Ca2+ channels (VGCCs) is functionally important, but little is known about the architecture of this region. In K+ channels, this part of the pore is formed by the S6/M2 transmembrane segments from four symmetrically arranged subunits. The Ca2+ channel pore, however, is formed by four asymmetric domains of the same (α1) subunit. Here we investigated the architecture of the inner pore of P/Q-type Ca2+ channels using the substituted-cysteine accessibility method. Many positions in the S6 segments of all four repeats of the α1 subunit (Cav2.1) were modified by internal methanethiosulfonate ethyltrimethylammonium (MTSET). However, the pattern of modification does not fit any known sequence alignment with K+ channels. In IIS6, five consecutive positions showed clear modification, suggesting a likely aqueous crevice and a loose packing between S6 and S5 segments, a notion further supported by the observation that some S5 positions were also accessible to internal MTSET. These results indicate that the inner pore of VGCCs is indeed formed by the S6 segments but is different from that of K+ channels. Interestingly some residues in IIIS6 and IVS6 whose mutations in L-type Ca2+ channels affect the binding of dihydropyridines and phenylalkylamines and are thought to face the pore appeared not to react with internal MTSET. Probing with qBBr, a rigid thiol-reactive agent with a dimension of 12 Å × 10 Å × 6 Å suggests that the inner pore can open to >10 Å. This work provides an impetus for future studies on ion permeation, gating, and drug binding of VGCCs.

scholarly journals Arrhythmia mutations in calmodulin cause conformational changes that affect interactions with the cardiac voltage-gated calcium channel

2018 ◽  
Vol 115 (45) ◽  
pp. E10556-E10565 ◽  
Author(s):  
Kaiqian Wang ◽  
Christian Holt ◽  
Jocelyn Lu ◽  
Malene Brohus ◽  
Kamilla Taunsig Larsen ◽  
...  
Keyword(s):  
Calcium Channel ◽  
Conformational Changes ◽  
Structural Changes ◽  
Voltage Gated ◽  
Cardiac Ion Channels ◽  
Disease Mutations ◽  
Dependent Inactivation ◽  
Ef Hand ◽  
Voltage Gated Calcium Channel ◽  
Structural Insights

Calmodulin (CaM) represents one of the most conserved proteins among eukaryotes and is known to bind and modulate more than a 100 targets. Recently, several disease-associated mutations have been identified in theCALMgenes that are causative of severe cardiac arrhythmia syndromes. Although several mutations have been shown to affect the function of various cardiac ion channels, direct structural insights into any CaM disease mutation have been lacking. Here we report a crystallographic and NMR investigation of several disease mutant CaMs, linked to long-QT syndrome, in complex with the IQ domain of the cardiac voltage-gated calcium channel (CaV1.2). Surprisingly, two mutants (D95V, N97I) cause a major distortion of the C-terminal lobe, resulting in a pathological conformation not reported before. These structural changes result in altered interactions with the CaV1.2 IQ domain. Another mutation (N97S) reduces the affinity for Ca2+by introducing strain in EF hand 3. A fourth mutant (F141L) shows structural changes in the Ca2+-free state that increase the affinity for the IQ domain. These results thus show that different mechanisms underlie the ability of CaM disease mutations to affect Ca2+-dependent inactivation of the voltage-gated calcium channel.

scholarly journals Localization of the Activation Gate of a Voltage-gated Ca2+ Channel

2005 ◽  
Vol 126 (3) ◽  
pp. 205-212 ◽  
Author(s):  
Cheng Xie ◽  
Xiao-guang Zhen ◽  
Jian Yang
Keyword(s):  
State Dependence ◽  
K Channels ◽  
Voltage Gated ◽  
Closed State ◽  
State Dependent ◽  
Transmembrane Voltage ◽  
Activation Gate ◽  
Pore Lining ◽  
Ca2 Channels ◽  
Α1 Subunit

Ion channels open and close in response to changes in transmembrane voltage or ligand concentration. Recent studies show that K+ channels possess two gates, one at the intracellular end of the pore and the other at the selectivity filter. In this study we determined the location of the activation gate in a voltage-gated Ca2+ channel (VGCC) by examining the open/closed state dependence of the rate of modification by intracellular methanethiosulfonate ethyltrimethylammonium (MTSET) of pore-lining cysteines engineered in the S6 segments of the α1 subunit of P/Q type Ca2+ channels. We found that positions above the putative membrane/cytoplasm interface, including two positions below the corresponding S6 bundle crossing in K+ channels, showed pronounced state-dependent accessibility to internal MTSET, reacting ∼1,000-fold faster with MTSET in the open state than in the closed state. In contrast, a position at or below the putative membrane/cytoplasm interface was modified equally rapidly in both the open and closed states. Our results suggest that the S6 helices of the α1 subunit of VGCCs undergo conformation changes during gating and the activation gate is located at the intracellular end of the pore.

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