共查询到20条相似文献,搜索用时 31 毫秒
1.
《Channels (Austin, Tex.)》2013,7(2):173-187
Invertebrate L-type calcium channel, LCav1, isolated from the pond snail Lymnaea stagnalis is nearly indistinguishable from mammalian Cav1.2 (α1C) calcium channel in biophysical characteristics observed in vitro. These L-type channels are likely constrained within a narrow range of biophysical parameters to perform similar functions in the snail and mammalian cardiovascular systems. What distinguishes snail and mammalian L-type channels is a difference in dihydropyridine sensitivity: 100 nM isradipine exhibits a significant block of mammalian Cav1.2 currents without effect on snail LCav1 currents. The native snail channel serves as a valuable surrogate for validating key residue differences identified from previous experimental and molecular modeling work. As predicted, three residue changes in LCav1 (N_3o18, F_3i10, and I_4i12) replaced with DHP-sensing residues in respective positions of Cav1.2, (Q_3o18, Y_3i10, and M_4i12) raises the potency of isradipine block of LCaV1 channels to that of mammalian Cav1.2. Interestingly, the single N_3o18_Q mutation in LCav1 channels lowers DHP sensitivity even further and the triple mutation bearing enhanced isradipine sensitivity, still retains a reduced potency of agonist, (S)-Bay K8644. 相似文献
2.
Taylor F. Dawson Adrienne N. Boone Adriano Senatore Joshua Piticaru Shano Thiyagalingam Daniel Jackson Angus Davison J. David Spafford 《PloS one》2014,9(4)
The accessory beta subunit (Cavβ) of calcium channels first appear in the same genome as Cav1 L-type calcium channels in single-celled coanoflagellates. The complexity of this relationship expanded in vertebrates to include four different possible Cavβ subunits (β1, β2, β3, β4) which associate with four Cav1 channel isoforms (Cav1.1 to Cav1.4) and three Cav2 channel isoforms (Cav2.1 to Cav2.3). Here we assess the fundamentally-shared features of the Cavβ subunit in an invertebrate model (pond snail Lymnaea stagnalis) that bears only three homologous genes: (LCav1, LCav2, and LCavβ). Invertebrate Cavβ subunits (in flatworms, snails, squid and honeybees) slow the inactivation kinetics of Cav2 channels, and they do so with variable N-termini and lacking the canonical palmitoylation residues of the vertebrate β2a subunit. Alternative splicing of exon 7 of the HOOK domain is a primary determinant of a slow inactivation kinetics imparted by the invertebrate LCavβ subunit. LCavβ will also slow the inactivation kinetics of LCav3 T-type channels, but this is likely not physiologically relevant in vivo. Variable N-termini have little influence on the voltage-dependent inactivation kinetics of differing invertebrate Cavβ subunits, but the expression pattern of N-terminal splice isoforms appears to be highly tissue specific. Molluscan LCavβ subunits have an N-terminal “A” isoform (coded by exons: 1a and 1b) that structurally resembles the muscle specific variant of vertebrate β1a subunit, and has a broad mRNA expression profile in brain, heart, muscle and glands. A more variable “B” N-terminus (exon 2) in the exon position of mammalian β3 and has a more brain-centric mRNA expression pattern. Lastly, we suggest that the facilitation of closed-state inactivation (e.g. observed in Cav2.2 and Cavβ3 subunit combinations) is a specialization in vertebrates, because neither snail subunit (LCav2 nor LCavβ) appears to be compatible with this observed property. 相似文献
3.
Valentina Taiakina Adrienne N. Boone Julia Fux Adriano Senatore Danielle Weber-Adrian J. Guy Guillemette J. David Spafford 《PloS one》2013,8(4)
NSCaTE is a short linear motif of (xWxxx(I or L)xxxx), composed of residues with a high helix-forming propensity within a mostly disordered N-terminus that is conserved in L-type calcium channels from protostome invertebrates to humans. NSCaTE is an optional, lower affinity and calcium-sensitive binding site for calmodulin (CaM) which competes for CaM binding with a more ancient, C-terminal IQ domain on L-type channels. CaM bound to N- and C- terminal tails serve as dual detectors to changing intracellular Ca2+ concentrations, promoting calcium-dependent inactivation of L-type calcium channels. NSCaTE is absent in some arthropod species, and is also lacking in vertebrate L-type isoforms, Cav1.1 and Cav1.4 channels. The pervasiveness of a methionine just downstream from NSCaTE suggests that L-type channels could generate alternative N-termini lacking NSCaTE through the choice of translational start sites. Long N-terminus with an NSCaTE motif in L-type calcium channel homolog LCav1 from pond snail Lymnaea stagnalis has a faster calcium-dependent inactivation than a shortened N-termini lacking NSCaTE. NSCaTE effects are present in low concentrations of internal buffer (0.5 mM EGTA), but disappears in high buffer conditions (10 mM EGTA). Snail and mammalian NSCaTE have an alpha-helical propensity upon binding Ca2+-CaM and can saturate both CaM N-terminal and C-terminal domains in the absence of a competing IQ motif. NSCaTE evolved in ancestors of the first animals with internal organs for promoting a more rapid, calcium-sensitive inactivation of L-type channels. 相似文献
4.
《Biophysical journal》2023,122(3):496-505
Cav1.1 is the voltage-gated calcium channel essential for the contraction of skeletal muscles upon membrane potential changes. Structural determination of the Cav1.1 channel opens the avenue toward understanding of the structure-function relationship of voltage-gated calcium channels. Here, we show that there exist two Ca2+-binding sites, termed S1 and S2, within the selectivity filter of Cav1.1 through extensive molecular dynamics simulations on various initial ion arrangement configurations. The formation of both binding sites is associated with the four Glu residues (Glu292/614/1014/1323) that constitute the so-called EEEE locus. At the S1 site near the extracellular side, the Ca2+ ion is coordinated with the negatively charged carboxylic groups of these Glu residues and of the Asp615 residue either in a direct way or via an intermediate water molecule. At the S2 site, Ca2+ binding shows two distinct states: an upper state involving two out of the four Glu residues in the EEEE locus and a lower state involving only one Glu residue. In addition, there exist two recruitment sites for Ca2+ above the entrance of the filter. These findings promote the understanding of mechanism for ion permeation and selectivity in calcium channels. 相似文献
5.
Voltage-activated Ca2+ channels are membrane protein machinery performing selective permeation of external calcium ions. The main Ca2+ selective filters of all high-voltage-activated Ca2+ channel isoforms are commonly composed of four Glu residues (EEEE), while those of low-voltage-activated T-type Ca2+ channel isoforms are made up of two Glu and two Asp residues (EEDD). We here investigate how the Asp residues at the pore loops of domains III and IV affect biophysical properties of the Cav3.2 channel. Electrophysiological characterization of the pore mutant channels in which the pore Asp residue(s) were replaced with Glu, showed that both Asp residues critically control the biophysical properties of Cav3.2, including relative permeability between Ba2+ and Ca2+, anomalous mole fraction effect (AMFE), voltage dependency of channel activation, Cd2+ blocking sensitivity, and pH effects, in distinctive ways. 相似文献
6.
《Channels (Austin, Tex.)》2013,7(3):154-156
Fluorophore-assisted light inactivation (FALI) is an investigative tool to inactivate fluorescently labeled proteins by a mechanism of in situ photodestruction. We found that Cav1.2 (L-type) and Cav3.1 (T-type) calcium channels, labeled by genetic fusion with GFP derivatives, show differential sensitivity to FALI. Specifically, FALI silences Cav1.2 calcium channels containing EYFP-labeled α1C subunits but does not affect the EYFP-α1G Cav3.1 calcium channels or Cav1.2 channels containing EYFP-labeled β subunits. Our findings limit the applicability of acceptor photobleaching for the measurements of FRET but open an opportunity to combine the fluorescent imaging of the live cell expressing labeled calcium channels with selective functional inactivation of their specific subsets. 相似文献
7.
《Channels (Austin, Tex.)》2013,7(1):25-31
Voltage-activated Cav1.2 calcium channels require association of the pore-forming α1C subunit with accessory Cavβ and α2δ subunits. Binding of a single calmodulin (CaM) to α1C supports Ca2+-dependent inactivation (CDI). The human Cav1.2 channel is silent in the absence of Cavβ and/or α2δ. Recently, we found that coexpression of exogenous CaM (CaMex) supports plasma membrane targeting, gating facilitation and CDI of the channel in the absence of Cavβ. Here we discovered that CaMex and its Ca2+-insensitive mutant (CaM1234) rendered active α1C/Cavβ channel in the absence of α2δ. Coexpression of CaMex with α1C and β2d in calcium-channel-free COS-1 cells recovered gating of the channel and supported CDI. Voltage-dependence of activation was shifted by ≈ +40 mV to depolarization potentials. The calcium current reached maximum at +40 mV (20 mM Ca2+) and exhibited approximately 3 times slower activation and 5 times slower inactivation kinetics compared to the wild-type channel. Furthermore, both CaMex and CaM1234 accelerated recovery from inactivation and induced facilitation of the calcium current by strong depolarization prepulse, the properties absent from the human vascular/neuronal Cav1.2 channel. The data suggest a previously unknown action of CaM that in the presence of Cavβ translates into activation of the α2δ-deficient calcium channel and alteration of its properties. 相似文献
8.
Flynn R Chen L Hameed S Spafford JD Zamponi GW 《Biochemical and biophysical research communications》2008,368(3):827-831
Rem2 belongs to the RGK family of small GTPases whose members are known to interact with the voltage gated calcium channel β subunit, and to inhibit or abolish calcium currents. To identify the underlying functional domains of Rem2, we created several N- or C-terminally truncated Rem2 proteins and examined their abilities to interact with the Cav β subunit and to regulate the activities of Cav2.2 N-type calcium channels. Confocal imaging of Rem2 in tsA-201 cells revealed that it contains a membrane-targeting signal in its C-terminus, consistent with previous studies. Co-precipitation assays showed that Cav β3 interaction depends on Rem2 residues 1-123. Only Rem2 proteins that targeted the cell membrane as well as bound the β subunit were able to reduce whole cell calcium currents. 相似文献
9.
Adriano Senatore Wendy Guan Adrienne N. Boone J. David Spafford 《The Journal of biological chemistry》2014,289(17):11952-11969
T-type (Cav3) channels are categorized as calcium channels, but invertebrate ones can be highly sodium-selective channels. We illustrate that the snail LCav3 T-type channel becomes highly sodium-permeable through exon splicing of an extracellular turret and descending helix in domain II of the four-domain Cav3 channel. Highly sodium-permeable T-type channels are generated without altering the invariant ring of charged residues in the selectivity filter that governs calcium selectivity in calcium channels. The highly sodium-permeant T-type channel expresses in the brain and is the only splice isoform expressed in the snail heart. This unique splicing of turret residues offers T-type channels a capacity to serve as a pacemaking sodium current in the primitive heart and brain in lieu of Nav1-type sodium channels and to substitute for voltage-gated sodium channels lacking in many invertebrates. T-type channels would also contribute substantially to sodium leak conductances at rest in invertebrates because of their large window currents. 相似文献
10.
11.
Didi Matza Abdallah Badou Kathryn G. Klemic Judith Stein Usha Govindarajulu Monica J. Nadler Jean-Pierre Kinet Amnon Peled Oz M. Shapira Leonard K. Kaczmarek Richard A. Flavell 《PloS one》2016,11(1)
The process of calcium entry in T cells is a multichannel and multi-step process. We have studied the requirement for L-type calcium channels (Cav1.1) α1S subunits during calcium entry after TCR stimulation. High expression levels of Cav1.1 channels were detected in activated T cells. Sequencing and cloning of Cav1.1 channel cDNA from T cells revealed that a single splice variant is expressed. This variant lacks exon 29, which encodes the linker region adjacent to the voltage sensor, but contains five new N-terminal exons that substitute for exons 1 and 2, which are found in the Cav1.1 muscle counterpart. Overexpression studies using cloned T cell Cav1.1 in 293HEK cells (that lack TCR) suggest that the gating of these channels was altered. Knockdown of Cav1.1 channels in T cells abrogated calcium entry after TCR stimulation, suggesting that Cav1.1 channels are controlled by TCR signaling. 相似文献
12.
Jeonghan Lee Michael T. Nelson Kirstin E. Rose Slobodan M. Todorovic 《Molecular neurobiology》2013,48(2):274-280
T-type calcium channels in the dorsal root ganglia (DRG) have a central function in tuning neuronal excitability and are implicated in sensory processing including pain. Previous studies have implicated redox agents in control of T-channel activity; however, the mechanisms involved are not completely understood. Here, we recorded T-type calcium currents from acutely dissociated DRG neurons from young rats and investigated the mechanisms of CaV3.2 T-type channel modulation by S-nitrosothiols (SNOs). We found that extracellular application of S-nitrosoglutathione (GSNO) and S-nitroso-N-acetyl-penicillamine rapidly reduced T-type current amplitudes. GSNO did not affect voltage dependence of steady-state inactivation and macroscopic current kinetics of T-type channels. The effects of GSNO were abolished by pretreatment of the cells with N-ethylmaleimide, an irreversible alkylating agent, but not by pretreatment with 1H-(1,2,4) oxadiazolo (4,3-a) quinoxalin-1-one, a specific soluble guanylyl cyclase inhibitor, suggesting a potential effect of GSNO on putative extracellular thiol residues on T-type channels. Expression of wild-type CaV3.2 channels or a quadruple Cys-Ala mutant in human embryonic kidney cells revealed that Cys residues in repeats I and II on the extracellular face of the channel were required for channel inhibition by GSNO. We propose that SNO-related molecules in vivo may lead to alterations of T-type channel-dependent neuronal excitability in sensory neurons and in the central nervous system in both physiological and pathological conditions such as neuronal ischemia/hypoxia. 相似文献
13.
Putative calcium‐binding domains of the Caenorhabditis elegans BK channel are dispensable for intoxication and ethanol activation
下载免费PDF全文
![点击此处可从《Genes, Brain & Behavior》网站下载免费的PDF全文](/ch/ext_images/free.gif)
S. J. Davis L. L. Scott G. Ordemann A. Philpo J. Cohn J. T. Pierce‐Shimomura 《Genes, Brain & Behavior》2015,14(6):454-465
Alcohol modulates the highly conserved, voltage‐ and calcium‐activated potassium (BK) channel, which contributes to alcohol‐mediated behaviors in species from worms to humans. Previous studies have shown that the calcium‐sensitive domains, RCK1 and the Ca2+ bowl, are required for ethanol activation of the mammalian BK channel in vitro. In the nematode Caenorhabditis elegans, ethanol activates the BK channel in vivo, and deletion of the worm BK channel, SLO‐1, confers strong resistance to intoxication. To determine if the conserved RCK1 and calcium bowl domains were also critical for intoxication and basal BK channel‐dependent behaviors in C. elegans, we generated transgenic worms that express mutated SLO‐1 channels predicted to have the RCK1, Ca2+ bowl or both domains rendered insensitive to calcium. As expected, mutating these domains inhibited basal function of SLO‐1 in vivo as neck and body curvature of these mutants mimicked that of the BK null mutant. Unexpectedly, however, mutating these domains singly or together in SLO‐1 had no effect on intoxication in C. elegans. Consistent with these behavioral results, we found that ethanol activated the SLO‐1 channel in vitro with or without these domains. By contrast, in agreement with previous in vitro findings, C. elegans harboring a human BK channel with mutated calcium‐sensing domains displayed resistance to intoxication. Thus, for the worm SLO‐1 channel, the putative calcium‐sensitive domains are critical for basal in vivo function but unnecessary for in vivo ethanol action. 相似文献
14.
15.
Woo Seung Son Kyu-Sung Jeong Sang Min Lim Ae Nim Pae 《Bioorganic & medicinal chemistry letters》2019,29(10):1168-1172
Highly effective and safe drugs for the treatment of neuropathic pain are urgently required and it was shown that blocking T-type calcium channels can be a promising strategy for drug development for neuropathic pain. We have developed pyrrolidine-based T-type calcium channel inhibitors by structural hybridization and subsequent assessment of in vitro activities against Cav3.1 and Cav3.2 channels. Profiling of in vitro ADME properties of compounds was also carried out. The representative compound 17h showed comparable in vivo efficacy to gabapentin in the SNL model, which indicates T-type calcium channel inhibitors can be developed as effective therapeutics for neuropathic pain. 相似文献
16.
The Nav1.2 and Nav1.3 voltage-gated sodium channel isoforms demonstrate distinct differences in their kinetics and voltage dependence of fast inactivation when expressed in Xenopus oocytes. Co-expression of the auxiliary β1 subunit accelerated inactivation of both the Nav1.2 and Nav1.3 isoforms, but it did not eliminate the differences, demonstrating that this property is inherent in the α subunit. By constructing chimeric channels between Nav1.2 and Nav1.3, we demonstrate that the carboxyl terminus is responsible for the differences. The Nav1.2 carboxyl terminus caused faster inactivation in the Nav1.3 backbone, and the Nav1.3 carboxyl terminus caused slower inactivation in the Nav1.2 channel. Through analysis of truncated channels, we identified a homologous 60-amino acid region within the carboxyl terminus of the Nav1.2 and the Nav1.3 channels that is responsible for this modulation of fast inactivation. Site-directed replacement of Nav1.3 lysine 1826 in this region to its Nav1.2 analogue glutamic acid 1880 (K1826E) shifted the voltage dependence of inactivation toward that of Nav1.2. The K1826E mutation also accelerated the inactivation kinetics to a level comparable with that of Nav1.2. The reverse Nav1.2 E1880K mutation exhibited much slower inactivation kinetics and depolarized inactivation voltage dependence. A complementary mutation located within the inactivation linker of Nav1.3 (K1453E) caused inactivation changes mirroring those caused by the K1826E mutation in Nav1.3. Therefore, we have identified a homologous carboxyl-terminal residue that regulates the kinetics and voltage dependence of fast inactivation in sodium channels, possibly via a charge-dependent interaction with the inactivation linker. 相似文献
17.
Díaz D Bartolo R Delgadillo DM Higueldo F Gomora JC 《The Journal of membrane biology》2005,207(2):91-105
Inorganic ions have been used widely to investigate biophysical properties of high voltage-activated calcium channels (HVA:
Cav1 and Cav2 families). In contrast, such information regarding low voltage-activated calcium channels (LVA: Cav3 family) is less documented. We have studied the blocking effect of Cd2+, Co2+ and Ni2+ on T-currents expressed by human Cav3 channels: Cav3.1, Cav3.2, and Cav3.3. With the use of the whole-cell configuration of the patch-clamp technique, we have recorded Ca2+ (2 mM) currents from HEK−293 cells stably expressing recombinant T-type channels. Cd2+ and Co2+ block was 2- to 3-fold more potent for Cav3.2 channels (EC50 = 65 and 122 μM, respectively) than for the other two LVA channel family members. Current-voltage relationships indicate
that Co2+ and Ni2+ shift the voltage dependence of Cav3.1 and Cav3.3 channels activation to more positive potentials. Interestingly, block of those two Cav3 channels by Co2+ and Ni2+ was drastically increased at extreme negative voltages; in contrast, block due to Cd2+ was significantly decreased. This unblocking effect was slightly voltage-dependent. Tail-current analysis reveals a differential
effect of Cd2+ on Cav3.3 channels, which can not close while the pore is occupied with this metal cation. The results suggest that metal cations
affect differentially T-type channel activity by a mechanism involving the ionic radii of inorganic ions and structural characteristics
of the channels pore. 相似文献
18.
Hak Kyun Yang Woo Seung Son Keon Seung Lim Gun Hee Kim Eun Jeong Lim Changdev G. Gadhe 《Journal of enzyme inhibition and medicinal chemistry》2018,33(1):1460-1471
The treatment of neuropathic pain is one of the urgent unmet medical needs and T-type calcium channels are promising therapeutic targets for neuropathic pain. Several potent T-type channel inhibitors showed promising in vivo efficacy in neuropathic pain animal models and are being investigated in clinical trials. Herein we report development of novel pyrrolidine-based T-type calcium channel inhibitors by pharmacophore mapping and structural hybridisation followed by evaluation of their Cav3.1 and Cav3.2 channel inhibitory activities. Among potent inhibitors against both Cav3.1 and Cav3.2 channels, a promising compound 20n based on in vitro ADME properties displayed satisfactory plasma and brain exposure in rats according to in vivo pharmacokinetic studies. We further demonstrated that 20n effectively improved the symptoms of neuropathic pain in both SNL and STZ neuropathic pain animal models, suggesting modulation of T-type calcium channels can be a promising therapeutic strategy for the treatment of neuropathic pain. 相似文献
19.
20.
《Channels (Austin, Tex.)》2013,7(4):320-324
Interactions between calmodulin (CaM) and voltage-gated calcium channels (Cavs) are crucial for Cav activity-dependent feedback modulation. We recently reported an X-ray structure that shows two Ca2+/CaM molecules bound to the Cav1.2 C terminal tail, one at the PreIQ region and one at the IQ domain. Surprisingly, the asymmetric unit of the crystal showed a dimer in which Ca2+/CaM bridged two PreIQ helixes to form a 4:2 Ca2+/CaM:Cav C-terminal tail assembly. Contrary to previous proposals based on a similar crystallographic dimer, extensive biochemical analysis together with subunit counting experiments of full-length channels in live cell membranes failed to find evidence for multimers that would be compatible with the 4:2 crossbridged complex. Here, we examine this possibility further. We find that CaM over-expression has no functional effect on Cav1.2 inactivation or on the stoichiometry of full-length Cav1.2. These data provide further support for the monomeric Cav1.2 stoichiometry. Analysis of the electrostatic surfaces of the 2:1 Ca2+/CaM:CaV C-terminal tail assembly reveals notable patches of electronegativity. These could influence various forms of channel modulation by interacting with positively charged elements from other intracellular channel domains. 相似文献