Molecular Determinants of Inactivation within the I-II Linker of α1E (CaV2.3) Calcium Channels

Berrou, Laurent; Bernatchez, Gérald; Parent, Lucie

doi:10.1016/s0006-3495(01)76008-0

Cited by 56 publications

(92 citation statements)

References 65 publications

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“…8). Although highly speculative, the model integrates related structure-function results from a number of different laboratories that point to the ␤ subunit D domain interaction with the ␣ 1 subunit I-II linker as a key determinant of Ca 2ϩ channel gating properties (Herlitze et al, 1997;Bourinet et al, 1999;Stotz et al, 2000;Berrou et al, 2001). Moreover, it incorporates results showing that regulation of activation and inactivation are separable functions of ␤ subunits (Olcese et al, 1994).…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, it incorporates results showing that regulation of activation and inactivation are separable functions of ␤ subunits (Olcese et al, 1994). Of particular relevance to our model are studies showing that the ␤ 1 subunit D domain was all that was required to reproduce the inactivation rate of L-type channels coexpressed with full-length ␤ 1 (Cens et al, 1999) and that a single point mutation (R378E) in the ␤ subunit binding site of the ␣ 1 I-II linker (AID domain) had a depolarizing effect on the voltage dependence of both activation and inactivation of an ␣ 1E subunit (Berrou et al, 2001). …”

Section: Discussionmentioning

confidence: 99%

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Alternative Splicing of the β₄Subunit Has α₁Subunit Subtype-Specific Effects on Ca²⁺Channel Gating

Helton

Horne

2002

J. Neurosci.

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Ca 2ϩ channel ␤ subunits are important molecular determinants of the kinetics and voltage dependence of Ca 2ϩ channel gating. Through direct interactions with channel-forming ␣ 1 subunits, ␤ subunits enhance expression levels, accelerate activation, and have variable effects on inactivation. Four distinct ␤ subunit genes each encode five homologous sequence domains (D1-5), three of which (D1, D3, and D5) undergo alternative splicing. We have isolated from human spinal cord a novel alternatively spliced ␤ 4 subunit containing a short form of domain D1 (␤ 4a ) that is highly homologous to N termini of Xenopus and rat ␤ 3 subunits. The purpose of this study was to compare the gating properties of various ␣ 1 subunit complexes containing ␤ 4a with those of complexes containing a ␤ 4 subunit with a longer form of domain D1, ␤ 4b . Expression in Xenopus oocytes revealed that, relative to ␣ 1A and ␣ 1B complexes containing ␤ 4b , the voltage dependence of activation and inactivation of complexes containing ␤ 4a were shifted to more depolarized potentials. Moreover, ␣ 1A and ␣ 1B complexes containing ␤ 4a inactivated at a faster rate. Interestingly, ␤ 4 subunit alternative splicing did not influence the gating properties of ␣ 1C and ␣ 1E subunits. Experiments with ␤ 4 deletion mutants revealed that both the N and C termini of the ␤ 4 subunit play critical roles in setting voltage-dependent gating parameters and that their effects are ␣ 1 subunit specific. Our data are best explained by a model in which distinct modes of activation and inactivation result from ␤-subunit splice variant-specific interactions with an ␣ 1 subunit gating structure. Key words: ␤4 subunit; alternative splicing; N terminus; calcium channel; gating; voltage clamp; spinal cordNeuronal high voltage-activated Ca 2ϩ channels (L, N, P/Q, and R) consist of at least four subunits, ␣ 1 , ␣ 2 /␦, and ␤ , with a fifth subunit, ␥, being recently described (Letts et al., 1998). Different Ca 2ϩ channel phenotypes arise primarily from the expression of five unique ␣ 1 subunit genes (␣ 1A -␣ 1E ). These genes encode large pore-forming proteins (Ͼ2200 amino acids) that are differentially distributed throughout the nervous system (Westenbroek et al., 1990(Westenbroek et al., , 1998. Synaptic N-, P/Q-, and R-type channels, formed by ␣ 1B , ␣ 1A , and ␣ 1E subunits, respectively, play a principal role in regulating neurotransmitter release (Turner et al., 1992;Takahashi and Momiyama, 1993;Wheeler et al., 1994;Wu et al., 1999).Ca 2ϩ channel ␤ subunits (subtypes 1-4) are highly homologous intracellular proteins with primary sequences ranging from 480 to 630 amino acids (for review, see Birnbaumer et al., 1998). The sequence can be divided into five domains on the basis of the regions of amino acid identity between subtypes. All ␤ subunits contain a highly conserved ␤ interaction domain (BID) in domain 4, which has been shown to interact with high affinity to an ␣ interaction domain (AID) on the I-II linker of ␣ 1 subunits (Pragnell et al., 1994;De Waard and Campbell,...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Alternative Splicing of the β₄Subunit Has α₁Subunit Subtype-Specific Effects on Ca²⁺Channel Gating

Helton

Horne

2002

J. Neurosci.

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“…Steady-state inactivation was determined using a one-pulse protocol with a 2-s conditioning pulse of varying amplitude followed by a test pulse at the voltage yielding the peak current and was applied at a frequency of 0.02 Hz. Normalized currents obtained at the test pulse (I/I max ) were fitted with a standard Boltzmann equation as described elsewhere (38,46,50). Recovery from inactivation was studied by using a paired-pulse protocol.…”

Section: Methodsmentioning

confidence: 99%

“…Each data point was reported as the mean of individual measurements Ϯ S.E. as described elsewhere (38,46,50). The free energy of activation was calculated using the midpotential of activation.…”

Section: Methodsmentioning

confidence: 99%

Cooperative Activation of the T-type CaV3.2 Channel

Demers-Giroux

Bourdin

Sauvé

et al. 2013

Journal of Biological Chemistry

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Background:The low activation threshold of T-type Ca V 3.2 channels is central to neuronal rhythmogenesis. Results: The S4-S5 linker of Domain II is functionally coupled with Domains II and III during channel activation. Conclusion: Activation of Ca V 3.2 requires a specific interaction between adjacent domains. Significance: Disrupting this protein interface could be a pharmacological strategy to decrease Ca 2ϩ influx in neuronal pathologies.

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“…This is a nonsilent mutation creating a Gly to Arg mutation (G511R). The resulting Ca V 1.2 (XhoI) channel (which will be referred to herein as the Ca V 1.2 control channel) displayed inactivation and activation kinetics similar to the wild-type Ca V 1.2 (35,36). Constructs were verified by restriction mapping after religation of the mutated fragment into the SacI/XhoI sites of the wild-type Ca V 1.2.…”

Section: ϫ4mentioning

confidence: 99%

The Role of the GX9GX3G Motif in the Gating of High Voltage-activated Ca2+ Channels

Raybaud

Dodier

Bissonnette

et al. 2006

Journal of Biological Chemistry

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The putative hinge point revealed by the crystal structure of the MthK potassium channel is a glycine residue that is conserved in many ion channels. In high voltage-activated (HVA) Ca V channels, the mid-S6 glycine residue is only present in IS6 and IIS6, corresponding to G422 and G770 in Ca V 1.2. Two additional glycine residues are found in the distal portion of IS6 (Gly 432 and Gly 436 in Ca V 1.2) to form a triglycine motif unique to HVA Ca V channels. Lethal arrhythmias are associated with mutations of glycine residues in the human L-type Ca 2؉ channel. Hence, we undertook a mutational analysis to investigate the role of S6 glycine residues in channel gating. In Ca V 1.2, ␣-helix-breaking proline mutants (G422P and G432P) as well as the double G422A/G432A channel did not produce functional channels. The macroscopic inactivation kinetics were significantly decreased with Ca V 1.2 wild type > G770A > G422A Х G436A Ͼ Ͼ G432A (from the fastest to the slowest). Mutations at position Gly 432 produced mostly nonfunctional mutants. Macroscopic inactivation kinetics were markedly reduced by mutations of Gly 436 to Ala, Pro, Tyr, Glu, Arg, His, Lys, or Asp residues with stronger effects obtained with charged and polar residues. Mutations within the distal GX 3 G residues blunted Ca 2؉ -dependent inactivation kinetics and prevented the increased voltage-dependent inactivation kinetics brought by positively charged residues in the I-II linker. In Ca V 2.3, mutation of the distal glycine Gly 352 impacted significantly on the inactivation gating. Altogether, these data highlight the role of the GX 3 G motif in the voltage-dependent activation and inactivation gating of HVA Ca V channels with the distal glycine residue being mostly involved in the inactivation gating.Voltage-dependent calcium channels are membrane-bound proteins that form large aqueous pores for the selective diffusion of Ca 2ϩ ions across the plasma membrane (1, 2). Native Ca 2ϩ channels are composed of the pore-forming Ca V ␣1, the disulfur-linked dimer Ca V ␣2␦, the intracellular Ca V ␤ subunits (␤1-␤4), and in some cases the Ca V ␥ subunit (3). To date, molecular cloning has identified the primary structures for 10 distinct calcium channel Ca V ␣ 1 subunits (1, 4 -9) that are classified into three main subfamilies according to their gating properties (Ca V 1, Ca V 2, and Ca V 3). Whereas all voltage-gated Ca 2ϩ channel ␣1 subunits activate and inactivate in response to membrane depolarization, the high voltage-activated (HVA) 2 Ca V 1 and Ca V 2 ␣1 subunits operate at markedly more positive membrane potentials than low voltage-activated Ca V 3 channel ␣1 subunits.In the absence of a crystal structure for these proteins, details regarding the structural determinants of the channel inner pore as well as the molecular mechanism underlying the activation of Ca V ␣1 subunits remain sketchy. Structural studies have revealed that the architecture of the ion-selective pore is conserved in the homologous ␣ subunit of different K ϩ channels (10 -15) with the ...

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Molecular Determinants of Inactivation within the I-II Linker of α1E (CaV2.3) Calcium Channels

Cited by 56 publications

References 65 publications

Alternative Splicing of the β₄Subunit Has α₁Subunit Subtype-Specific Effects on Ca²⁺Channel Gating

Alternative Splicing of the β₄Subunit Has α₁Subunit Subtype-Specific Effects on Ca²⁺Channel Gating

Cooperative Activation of the T-type CaV3.2 Channel

The Role of the GX9GX3G Motif in the Gating of High Voltage-activated Ca2+ Channels

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Molecular Determinants of Inactivation within the I-II Linker of α1E (CaV2.3) Calcium Channels

Cited by 56 publications

References 65 publications

Alternative Splicing of the β4Subunit Has α1Subunit Subtype-Specific Effects on Ca2+Channel Gating

Alternative Splicing of the β4Subunit Has α1Subunit Subtype-Specific Effects on Ca2+Channel Gating

Cooperative Activation of the T-type CaV3.2 Channel

The Role of the GX9GX3G Motif in the Gating of High Voltage-activated Ca2+ Channels

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Alternative Splicing of the β₄Subunit Has α₁Subunit Subtype-Specific Effects on Ca²⁺Channel Gating

Alternative Splicing of the β₄Subunit Has α₁Subunit Subtype-Specific Effects on Ca²⁺Channel Gating