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J Biol Chem, Vol. 275, Issue 13, 9239-9243, March 31, 2000

Three New Familial Hemiplegic Migraine Mutants Affect P/Q-type Ca²⁺ Channel Kinetics^*

Richard L. Kraus, Martina J. Sinnegger, Alexandra Koschak, Hartmut Glossmann, Stefania Stenirri^§, Paola Carrera^§, and Jörg Striessnig^¶

From the Institut für Biochemische Pharmakologie, Peter-Mayr-Strasse 1, Innsbruck A-6020, Austria, and the ^§ Clinical Molecular Biology Laboratory, Hospitale San Raffaele, Milan 20132, Italy

	ABSTRACT

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

Missense mutations in the pore-forming human _1A subunit of neuronal P/Q-type Ca²⁺ channels are associated with familial hemiplegic migraine. We studied the functional consequences on P/Q-type Ca²⁺ channel function of three recently identified mutations, R583Q, D715E, and V1457L after introduction into rabbit _1A and expression in Xenopus laevis oocytes. The potential for half-maximal channel activation of Ba²⁺ inward currents was shifted by > 9 mV to more negative potentials in all three mutants. The potential for half-maximal channel inactivation was shifted by > 7 mV in the same direction in R583Q and D715E. Biexponential current inactivation during 3-s test pulses was significantly faster in D715E and slower in V1457L than in wild type. Mutations R583Q and V1457L delayed the time course of recovery from channel inactivation. The decrease of peak current through R583Q (30.2%) and D715E (30.1%) but not V1457L (18.7%) was more pronounced during 1-Hz trains of 15 100-ms pulses than in wild type (18.2%). Our data demonstrate that the mutations R583Q, D715E, and V1457L, like the previously reported mutations T666M, V714A, and I1819L, affect P/Q-type Ca²⁺ channel gating. We therefore propose that altered channel gating represents a common pathophysiological mechanism in familial hemiplegic migraine.

	INTRODUCTION

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

Voltage-gated P/Q-type Ca²⁺ channels are expressed on cell bodies and dendrites of cerebellar Purkinje cells and other neurons (1-3) where they are thought to control neuronal excitability, gene expression, neuronal plasticity, and differentiation. These channels are also expressed on presynaptic terminals (3) mediating depolarization-induced Ca²⁺ influx tightly coupled to neurotransmitter release (4). The Ca²⁺-selective pore of P/Q-type Ca²⁺ channels is formed by _1A subunits, which also contain the voltage sensors. _1A is encoded by the human gene CACNA1A on chromosome 19p13 (5).

P/Q-type Ca²⁺ channels have received much attention recently because CACNA1A mutations have been described which are responsible for at least three different neurological human diseases: episodic ataxia type 2 (EA-2),¹ spinocerebellar ataxia type 6, and familial hemiplegic migraine (FHM) with and without cerebellar ataxia. These mutations may provide important insight into how altered Ca²⁺ signaling and neuronal excitability can lead to neurodegeneration and episodic neurological diseases such as migraine.

Four nonsense mutations (6-8), three splice site mutations, and four deletions in CACNA1A (5, 7) have been found to segregate in patients with EA-2. Small CAG expansions were observed in a large series of patients with spinocerebellar ataxia type 6 (9), and a further CACNA1A missense mutation was identified in a patient with severe progressive ataxia (10). At least seven missense mutations have been identified in families with FHM (5, 11-13). Defects in the _1A gene are also responsible for the phenotypes (absence epilepsy and ataxia) of tottering (tg) and leaner (tg^la) mutant mice (14) and may also occur in more common forms of migraine (15).

The mechanisms by which these mutations cause these abnormal phenotypes is unclear. Mutations causing EA-2, an autosomal dominant disease, are predicted to give rise to truncated, presumably nonfunctional _1A proteins.² This must result in a partial loss of P/Q-type Ca²⁺ channel function.

In contrast, we (16) and others (17) have shown recently that _1A missense mutations causing FHM do not prevent channel activity. FHM is a rare autosomal dominant form of migraine with aura, associated with ictal hemiparesis and, in some families, with cerebellar ataxia and atrophy (18). Functional expression of rabbit _1A subunits containing the FHM mutations T666M, V714A, and I1811L revealed mutation-induced changes in gating kinetics altering the extent to which P/Q-type channels accumulate in inactivation during trains of depolarizing pulses. We therefore proposed that this could alter Ca²⁺ influx and signaling during episodes of high neuronal activity. This in turn might result in a long term activation of neurons within the proposed "migraine generator" in the brainstem discovered by brain imaging in migraine patients (19).

Essentially the same changes in gating kinetics were reported by Hans et al. (17) after introduction of the same FHM mutations in human _1A followed by heterologous expression in human embryonic kidney 293 cells and patch clamp analysis. In addition, they reported mutation-induced changes in single channel kinetics and expression density.

In the current study we examined the functional effects of three recently published FHM mutations, R583Q, D715E, and V1457L (11-13) to address further the important questions of whether all FHM mutations yield functional Ca²⁺ channels and if altered channel gating represents a key pathophysiological principle in FHM as proposed from initial studies.

	EXPERIMENTAL PROCEDURES

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

Mutant _1A cDNAs-- Mutations were introduced into rabbit class A Ca²⁺ channel _1A cDNA (BI-II, 1) by applying the "gene-SOEing" technique (20) as described previously (21). Nucleotide positions of endonuclease restriction sites are given in parentheses. _1A mutants were cloned into the polyadenylating transcription plasmids pSPCBI-2 (1) or pNKS2 (a gift of O. Pongs).

Single mutants R583Q and D715E were constructed according to the previously described procedure for generation of single mutants T666M and V714A (16).

Mutation V1457L (corresponding to V1465L in rabbit _1A, see legend to Fig. 1) as well as a silent mutation (codon for rabbit Asp-1545 GAC to GAT) were introduced simultaneously into rabbit class A cDNA by polymerase chain reaction to yield a ClaI restriction sequence. The mutated polymerase chain reaction fragment was cut SfiI (4290)-ClaI* (4925) and coligated with a NheI (3543)-SfiI (4290) fragment of BI-II into AL20 NheI (3543)-ClaI (homologous position to ClaI*) (22) to yield complete rabbit _1A cDNA sequence.

All polymerase chain reaction-generated fragments were sequenced completely to confirm sequence integrity.

Expression of _1A Mutants in Xenopus laevis Oocytes-- Preparation of stage V-VI oocytes from X. laevis and injection of cRNA are described in detail elsewhere (21). Capped run-off poly(A)⁺ cRNA transcripts from XbaI-linearized cDNA templates were synthesized according to the procedures of Krieg and Melton (23). ₁ cRNAs were coinjected with _1a (24) and ₂- (25) subunit cRNAs. To exclude effects of endogenous Ca²⁺-activated Cl currents on current kinetics, experiments were carried out in oocytes previously injected with 50-100 nl of a 0.1 M BAPTA solution.

Electrophysiological Recordings-- Inward Ba²⁺ currents (I_Ba) through expressed channel complexes were measured using the two-microelectrode voltage clamp technique as described previously (21). Similar current amplitudes were obtained with mutant and wild-type _1A subunits. Oocytes expressing peak I_Ba smaller than 400 nA or larger than 1.8 µA were excluded from analysis. Data analysis and acquisition were performed by using the pClamp software package (version 6.0, Axon Instruments).

Recordings were carried out at room temperature in a bath solution containing 40 mM Ba(OH)₂, 50 mM NaOH, 2 mM CsOH, 5 mM HEPES, adjusted to a pH of 7.4 with methanesulfonic acid. Voltage recording and current injecting microelectrodes were filled with 2.8 M CsCl, 0.2 M CsOH, 10 mM EGTA, 10 mM HEPES (adjusted to pH 7.4 with HCl) and had resistances of 0.3-2 megohm.

Recovery of I_Ba from inactivation was studied using a double-pulse protocol. After a 3-s depolarizing prepulse to +10 mV (holding potential 80 mV) the time course of I_Ba recovery was determined at 60 mV by applying 300-ms test pulses to +10 mV at various time intervals after the prepulse. Peak I_Ba was normalized to the peak current amplitude measured during the prepulse. I_Ba was then allowed to recover for 1 min at 100 mV. This double-pulse protocol was repeated individually for each recovery time interval in the same oocyte.

The voltage dependence of inactivation (steady-state inactivation) was determined from normalized inward currents elicited during steps to +10 mV after 10-s steps to various holding potentials. The voltage dependence of activation was determined from I-V curves obtained by step depolarizations from a holding potential of 80 mV to various test potentials. The half-maximal voltage for activation (V_0.5,act), the slope factor of the curve at V_0.5,act (k_act,), the half-maximal voltage for steady-state inactivation (V_0.5,_inact), and the slope factor of the curve (k_inact) were obtained by fitting the data to the Boltzmann equation. Apparent reversal potentials were calculated by extrapolation from I-V relationships.

Data Analysis-- Nonlinear least square fitting and statistical calculations were performed using Origin^R 5.0 (Microcal). Data are given as means ± S.E. for the indicated number of experiments.

	RESULTS

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

Mutations R583Q, D715E, and V1457L, illustrated in Fig. 1A, are located in highly conserved and functionally important regions of the human _1A subunit of neuronal P/Q-type Ca²⁺ channels. Mutation R583Q neutralizes a positive charge in transmembrane segment S4 of the channel in domain II (IIS4). S4 segments form part of the voltage sensor of voltage-gated Ca²⁺ channels (26). D715E is located in IIS6 adjacent to mutation V714A analyzed in our previous study and V1457L in the S5-S6 linker of domain III. Segments S5 and S6 and their connecting linkers are assumed to form the pore of the channel (26). We introduced the single mutations into the corresponding positions of the highly homologous rabbit _1A subunit (wild type, Ref. 1) and analyzed mutant channels for changes in their biophysical properties after functional expression in X. laevis oocytes (together with accessory ₁ and ₂- subunits) using the two-microelectrode voltage clamp technique.

View larger version (33K): [in this window] [in a new window]   Fig. 1.   FHM mutations alter Ca2+ current kinetics. Panel A, proposed folding structure of Ca2+ channel 1 subunits. The approximate positions of the new identified FHM mutations are indicated by black circles, previously reported FHM mutations (16) by open circles. Human mutation V1457L corresponds to V1465L in rabbit 1A. Panel B, IBa elicited by 3-s depolarizations from a holding potential of 80 mV to a test potential of +10 mV. Traces were normalized to the peak current amplitude. Normalized representative current traces are shown (cells: wild type (WT), R7813001; R583Q, R0804046; D715E, R0508006; V1457L, R3103030). Traces were fitted to a biexponential decay yielding the following time constants for the fast (fast) and slow (slow) component: wild type: 0.222, 0.897 s; R583Q: 0.205, 0.779 s; D715E: 0.141, 0.564 s; V1457L: 0.252, 1.255 s. Panel C, effect of mutations on fast and slow.  was calculated as in panel B. Data are the means ± S.E. for n = 5-20. Statistical significance (p < 0.01) is indicated by asterisks. fast: wild type, 0.228 ± 0.014 s; R583Q, 0.197 ± 0.008 s; D715E, 0.142 ± 0.004 s; V1457L, 0.252 ± 0.007 s. slow: wild type, 0.806 ± 0.077 s; R583Q, 0.789 ± 0.017 s; D715E, 0.578 ± 0.008 s; V1457L, 1.229 ± 0.034 s.

The potential for half-maximal activation (V_0.5,act) was significantly (p < 0.01) shifted to hyperpolarized potentials for all three mutants without changing the steepness of the steady-state activation curve (Table I). This effect was most pronounced in D715E. The midpoint voltage for steady-state inactivation was not altered in mutant V1457L, but a significant shift to more negative potentials occurred in R583Q and D715E (Table I). Apparent reversal potentials were similar for all constructs (53-59 mV) ruling out major changes in Ba²⁺ permeability.

To investigate whether the FHM mutations affect the time course of channel inactivation we analyzed the current decay during 3-s test pulses elicited from a holding potential of 80 mV to +10 mV (Fig. 1B). For wild-type and mutant channels the time course of inactivation could be well described by a double-exponential function. D715E significantly (p < 0.01) accelerated both the time constant for the initial fast component (_fast = 0.142 ± 0.004 s, n = 15) and the slow component (_slow = 0.577 ± 0.008 s, n = 15) of current decay compared with wild type (_fast = 0.227 ± 0.013 s; _slow = 0.806 ± 0.076 s, n = 5) (Fig. 1C). Mutation V1457L increased the time constant for the slow component of the current decay (_slow = 1.2 ± 0.033 s, n = 11). In R583Q _fast was also slightly accelerated, but this did not reach the level of statistical significance. The contribution of the fast component (wild type: 43.8 ± 2.0%, n = 5) was increased significantly in D715E (57.8 ± 1.5%, n = 14; p < 0.01) and decreased in V1457L (27.4 ± 2.3%, n = 10, p < 0.01).

Next we tested whether the mutations also change the extent of peak I_Ba decrease during pulse trains which reflects accumulation of channels in inactivation. Application of 15 100-ms pulses from a holding potential of 60 mV to a test potential of +10 mV at a frequency of 1 Hz caused a significant (p < 0.01) increase of accumulation in inactivation for mutants R583Q and D715E but not V1457L. Current decay after 15 pulses was 1.6-fold larger in R583Q (30.2 ± 0.8%; n = 35) and D715E (30.1 ± 1.5%; n = 18) than in wild type (19.1 ± 1%; n = 19) (Fig. 2, A and B).

View larger version (18K): [in this window] [in a new window]   Fig. 2.   Mutations affect IBa decay during 1-Hz pulse trains. Panel A, 1-Hz trains of 15 100-ms pulses were applied from a holding potential of 60 mV to a test potential of +10 mV. Peak currents during each pulse were normalized to the peak IBa during the first pulse (control) and are plotted against pulse number. Peak IBa decay after 15 pulses (given in percent of the control current) was as follows: wild type (WT), 19 ± 1; R583Q, 30 ± 0.8; D715E, 30 ± 1.4; V1457A, 19 ± 0.7 (means ± S.E., n = 18-35). Panel B, representative current traces are shown for wild type (cell R7731c74), R583Q (cell R3103043), D715E (cell R0508013), and V1457L (cell R3103023).

The fraction of channels inactivating during frequent depolarizations not only depends on the inactivation rate during the pulses but also on the rate of recovery from inactivation between pulses. Therefore recovery from inactivation was measured employing a double-pulse protocol (Fig. 3A). Channels were inactivated by a 3-s conditioning prepulse from 80 to +10 mV. The time course of recovery was then determined at 60 mV by applying 300-ms test pulses to +10 mV after various time intervals after the prepulse (Fig. 3A). Between single double-pulse experiments the oocytes were held at 100 mV for 60 s to allow full recovery of I_Ba. Recovery was determined at 60 mV to maximize the difference between wild-type and mutant channels. In wild-type and mutant channels about 90% of I_Ba recovered after 20 s. In all constructs recovery of I_Ba followed a biexponential time course (Fig. 3B). In both R583Q and V1457L the fraction of recovered current at all time intervals measured was significantly smaller (p < 0.01) than in wild type. No change was observed for D715E (Fig. 3B).

View larger version (27K): [in this window] [in a new window]   Fig. 3.   Mutations affect IBa recovery from inactivation. Panel A, recovery from inactivation was measured using a double-pulse protocol. After a 3-s depolarizing prepulse to +10 mV (holding potential 80 mV) the time course of IBa was determined at 60 mV by applying 300-ms test pulses to +10 mV at various time intervals after the prepulse. A representative trace of a recovery experiment for R583Q (cell R1205027) is illustrated. Panel B, fractional IBa recovery from inactivation after various periods of time (0.05, 0.1, 0.2, 0.5, 1, 2, 3, 5, 10, 15, 20 s). Note that fractional recoveries of R583Q and V715L were statistically different from wild type (WT) (p < 0.01) at all time points tested. The inset shows fractional current recovery after selected time points (0.5, 3, and 15 s) for clarity. Statistical significance (p < 0.01) is indicated by asterisks. Means ± S.E. are given for n = 5-20.

In summary, our experiments convincingly show that all newly discovered _1A mutations in patients with FHM cause abnormal gating behavior of P/Q-type Ca²⁺ channels. Gating changes therefore seem to represent an elementary mechanism underlying P/Q-type Ca²⁺ channel dysfunction in FHM.

	DISCUSSION

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

We have studied the functional consequences of three recently identified FHM missense mutations, R583Q, D715E, and V1457L within the _1A subunit of neuronal P/Q-type Ca²⁺ channels. None of the mutations resulted in a nonfunctional channel as proposed for EA-2 mutations in the _1A subunit gene. EA-2 mutations (5, 7) are believed to be incompatible with the expression of a functional protein. In the presence of an unaffected gene, it is therefore likely that the observed neurological phenotype in EA-2 results from a reduced activity of P/Q-type Ca²⁺ channels in the central nervous system. Instead, two independent mechanisms can affect P/Q-type currents in FHM patients: altered expression density and changes in channel gating. Hans et al. (17) have recently found that FHM mutations decrease or increase the density of functional P/Q-type currents after heterologous expression in Xenopus oocytes or mammalian cells. It is difficult to predict if these changes of expression density also occur in vivo where, in addition to the accessory ₂- and  subunits, _1A interacts with a number of other modulatory proteins such as G-proteins (27), calmodulin (28), and synaptic vesicle proteins (29). Clearly, this important question can only be addressed in animal models containing the respective mutations.

A second mechanism by which FHM mutations can affect P/Q-type Ca²⁺ currents is by changing channel gating. Our electrophysiological analysis provides convincing evidence that such changes also occur in three recently identified FHM mutations. Together with our previous results (16) this allows us to conclude that, irrespective of changes in expression density, this represents an elementary functional alteration underlying P/Q-type Ca²⁺ channel dysfunction in FHM.

As for T666M, V714A, and I1811L, all three new mutations significantly shifted the voltage dependence of activation to more negative potentials. In the absence of changes in the slope of the activation curve this must result in a more negative threshold of Ca²⁺ channel activation. This could lead to altered Ca²⁺ signaling by increasing P/Q-type Ca²⁺ channel activity at weak depolarizations. Two of the mutations also caused a more pronounced decrease of I_Ba during pulse trains, reflecting altered accumulation of channels in inactivation. This can result from either increased inactivation during the pulse or delayed recovery from inactivation between pulses. Our experiments demonstrate that it is due to slower recovery from inactivation in R583Q and faster inactivation in D715E. In V1457L decrease of I_Ba during the train was not different from wild type. This can be explained by the slower inactivation kinetics, which are counteracted by the slowed recovery from inactivation. Altered accumulation of channels in inactivation during rapid depolarizations could cause changes in Ca²⁺ influx especially during high but not during low neuronal activity. This may underlie the episodic character of FHM with attacks triggered by sensory or emotional stimuli.

In addition to the potential insight into the pathophysiology of migraine, mutations R583Q and D715E also provide us with interesting molecular information about channel function. As in the previously analyzed mutant R192Q (16), R583Q eliminates a conserved positive charge at the extracellular side of transmembrane S4-helix, which forms part of the voltage sensor of the channel. The charge neutralization at position 583 in IIS4 (R583Q) shifted the voltage dependence of activation (and inactivation) to more negative potentials and slowed recovery from inactivation. These findings indicate that not only mutations in the putative pore region (T666M, V714A, I1811L) but also in the S4 segments can alter _1A recovery from inactivation. This illustrates that conformational changes of voltage-sensing portions of _1A are involved in this process.

Mutation R583Q caused a negative shift of V_0.5,act without a change in the apparent gating charge, z_g (Table I). Based on a simplified model describing the gating of a channel with only two states (open and closed) (Equation 2-22 in Ref. 30; 31) a negative shift of V_0.5,act suggests that this mutation decreases the conformational energy difference between the closed and open states.

By assuming a model in which the voltage sensors in all four repeats move independently it can be predicted that Arg-583 (in IIS4) forms part of a voltage sensor which moves over potentials close to those causing channel opening. This is in contrast to data reported earlier for an _1S (skeletal muscle)/_1C (cardiac muscle) chimera where this was observed for sensors in repeats I and III but not in repeat II. Therefore this naturally occurring mutation clearly demonstrates that voltage sensor movements vary not only between different voltage-dependent cation channels (31) but even between different Ca²⁺ channel ₁ subunits.

Mutation D715E is located adjacent to mutation V714A. Together with I1811L in IVS6 these are believed to be located close to the cytoplasmic mouth of the pore. Unlike V714A and I1811L, D715E did not affect recovery from inactivation and prominently accelerated current inactivation upon depolarization. These data indicate that the cytoplasmic end of S6 helices comprise a functionally relevant region within _1A which tightly controls the channel's inactivation properties. Although our data do not allow us to propose a defined molecular mechanism for this process they clearly show that even minor structural changes such as the introduction of a single side chain methyl group in mutant D715E are sufficient to disturb this functional domain.

The present work clearly shows that mutations in the human CACNA1A gene alter the gating properties of neuronal P/Q-type Ca²⁺ channels in all seven FHM mutants analyzed so far. This provides a rational basis for the generation of mutant mice containing selected mutations. Introduction of FHM mutations differing with respect to their biophysical properties should enable electrophysiological analysis of the consequences of altered channel gating for neuronal Ca²⁺ signaling in FHM and more common forms of migraine (15).

	ACKNOWLEDGEMENTS

We thank E. Wappl and E. Emberger for help in construction of mutants and P. Dietl for critical comments on the manuscript.

	FOOTNOTES

^* This work was supported in part by Fonds zur Förderung der Wissenschaftlichen Forschung Grants P-12641 (to J. S.) and P-12689 (to H. G.) and by the Österreichische Nationalbank (to J. S.), the Dr. Legerlotz Foundation, and the University of Innsbruck.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

Recipient of a Hertha-Firnberg fellowship.

^¶ To whom correspondence should be addressed. Tel.: 43-512-507-3164; Fax: 43-512-588-627; E-mail: joerg.striessnig@uibk.ac.at.

² D. Kullmann, personal communication.

	ABBREVIATIONS

The abbreviations used are: EA-2, episodic ataxia type 2; FHM, familial hemiplegic migraine; BAPTA, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; I_Ba, inward Ba²⁺ currents; V_0.5, act, half-maximal voltage for activation; k_act, slope factor of the curve at V_0.5,act; V_0.5, _inact, half-maximal voltage for steady-state inactivation; k_inact, slope factor of the curve at V_0.5,act.

	REFERENCES

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

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				A. Ducros, C. Denier, A. Joutel, M. Cecillon, C. Lescoat, K. Vahedi, F. Darcel, E. Vicaut, M.-G. Bousser, and E. Tournier-Lasserve The Clinical Spectrum of Familial Hemiplegic Migraine Associated with Mutations in a Neuronal Calcium Channel N. Engl. J. Med., July 5, 2001; 345(1): 17 - 24. [Abstract] [Full Text] [PDF]

				E. Wappl, J. Mitterdorfer, H. Glossmann, and J. Striessnig Mechanism of Dihydropyridine Interaction with Critical Binding Residues of L-type Ca2+ Channel alpha 1 Subunits J. Biol. Chem., April 13, 2001; 276(16): 12730 - 12735. [Abstract] [Full Text] [PDF]

				S. Berjukow, R. Marksteiner, S. Sokolov, R. G. Weiss, E. Margreiter, and S. Hering Amino Acids in Segment IVS6 and beta -Subunit Interaction Support Distinct Conformational Changes during Cav2.1 Inactivation J. Biol. Chem., May 11, 2001; 276(20): 17076 - 17082. [Abstract] [Full Text] [PDF]

				S. C. Stotz and G. W. Zamponi Identification of Inactivation Determinants in the Domain IIS6 Region of High Voltage-activated Calcium Channels J. Biol. Chem., August 24, 2001; 276(35): 33001 - 33010. [Abstract] [Full Text] [PDF]

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