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Voltage-Gated Calcium Channels Downloaded from http://cshperspectives.cshlp.org/ on October 5, 2021 - Published by Cold Spring Harbor Laboratory Press Voltage-Gated Calcium Channels William A. Catterall Department of Pharmacology, University of Washington, Seattle, Washington 98195-7280 Correspondence: [email protected] Voltage-gated calcium (Ca2þ) channels are key transducers of membrane potential changes into intracellular Ca2þ transients that initiate many physiological events. There are ten members of the voltage-gated Ca2þ channel family in mammals, and they serve distinct roles in cellular signal transduction. The CaV1 subfamily initiates contraction, secretion, regulation of gene expression, integration of synaptic input in neurons, and synaptic trans- mission at ribbon synapses in specialized sensory cells. The CaV2 subfamily is primarily responsible for initiation of synaptic transmission at fast synapses. The CaV3 subfamily is important for repetitive firing of action potentials in rhythmically firing cells such as cardiac myocytes and thalamic neurons. This article presents the molecular relationships and physiological functions of these Ca2þ channel proteins and provides information on their molecular, genetic, physiological, and pharmacological properties. PHYSIOLOGICAL ROLES OF with ryanodine-sensitive Ca2þ release channels VOLTAGE-GATED Ca2þ CHANNELS in the sarcoplasmic reticulum and activate them to initiate rapid contraction (Catterall 1991; a2þ channels in many different cell types Tanabe et al. 1993). The same Ca2þ channels Cactivate on membrane depolarization and in the transverse tubules also mediate a slow mediate Ca2þ influx in response to action Ca2þ conductance that increases cytosolic potentials and subthreshold depolarizing sig- concentration and thereby regulates the force nals. Ca2þ entering the cell through voltage- of contraction in response to high-frequency gated Ca2þ channels serves as the second trains of nerve impulses (Catterall 1991). In messenger of electrical signaling, initiating endocrine cells, voltage-gated Ca2þ channels many different cellular events (Fig. 1). In car- mediate Ca2þ entry that initiates secretion of diac and smooth muscle cells, activation of hormones (Yang and Berggren 2006). In neu- Ca2þ channels initiates contraction directly by rons, voltage-gated Ca2þ channels initiate syn- increasing cytosolic Ca2þ concentration and aptic transmission (Tsien et al. 1988; Dunlap indirectly by activating calcium-dependent et al. 1995; Catterall and Few 2008). In many calcium release by ryanodine-sensitive Ca2þ different cell types, Ca2þ entering the cytosol release channels in the sarcoplasmic reticulum via voltage-gated Ca2þ channels regulates en- (Reuter 1979; Tsien 1983; Bers 2002). In skeletal zyme activity, gene expression, and other muscle cells, voltage-gated Ca2þ channels in the biochemical processes (Flavell and Greenberg transverse tubule membranes interact directly 2008). Thus, voltage-gated Ca2þ channels are Editors: Martin Bootman, Michael J. Berridge, James W. Putney, and H. Llewelyn Roderick Additional Perspectives on Calcium Signaling available at www.cshperspectives.org Copyright # 2011 Cold Spring Harbor Laboratory Press; all rights reserved; doi: 10.1101/cshperspect.a003947 Cite this article as Cold Spring Harb Perspect Biol 2011;3:a003947 1 Downloaded from http://cshperspectives.cshlp.org/ on October 5, 2021 - Published by Cold Spring Harbor Laboratory Press W.A. Catterall Ca2+ α 2 δ γ α1 β Contraction Secretion Synaptic transmission Protein Enzyme phosphorylation regulation Nucleus Gene transcription Figure 1. Signal transduction by voltage-gated Ca2þ channels. Ca2þ entering cells initiates numerous intracel- lular events, including contraction, secretion, synaptic transmission, enzyme regulation, protein phosphoryla- tion/dephosphorylation, and gene transcription. (Inset) Subunit structure of voltage-gated Ca2þ channels. The five-subunit complex that forms high-voltage-activated Ca2þ channels is illustrated with a central pore- forming a1 subunit, a disulfide-linked glycoprotein dimer of a2 and d subunits, an intracellular b subunit, and a transmembrane glycoprotein g subunit (in some Ca2þ channel subtypes). As described in the text, this model is updated from the original description of the subunit structure of skeletal muscle Ca2þ channels. (Adapted from Takahashi et al. 1987). the key signal transducers of electrical excit- types of Ca2þ currents as defined by physiolog- ability, converting the electrical signal of the ical and pharmacological criteria (Tsien et al. action potential in the cell surface membrane 1988; Bean 1989a; Llina´s et al. 1992). In cardiac, to an intracellular Ca2þ transient. Signal trans- smooth, and skeletal muscle, the major Ca2þ duction in different cell types involves differ- currents are distinguished by high voltage ent molecular subtypes of voltage-gated Ca2þ of activation, large single channel conductance, channels, which mediate voltage-gated Ca2þ slow voltage-dependent inactivation, marked currents with different physiological, pharma- up-regulation by cAMP-dependent protein cological, and regulatory properties. phosphorylation pathways, and specific inhi- bition by Ca2þ antagonist drugs including 2þ dihydropyridines, phenylalkylamines, and ben- Ca CURRENT TYPES DEFINED BY zothiazepines (Table 1) (Reuter 1979; Tsien PHYSIOLOGICAL AND et al. 1988). These Ca2þ currents have been PHARMACOLOGICAL PROPERTIES designated L-type, as they have slow voltage- Since the first recordings of Ca2þ currents in dependent inactivation and therefore are long cardiac myocytes (reviewed in Reuter 1979), it lasting when Ba2þ is the current carrier and there has become apparent that there are multiple is no Ca2þ-dependent inactivation (Tsien et al. 2 Cite this article as Cold Spring Harb Perspect Biol 2011;3:a003947 Downloaded from http://cshperspectives.cshlp.org/ on October 5, 2021 - Published by Cold Spring Harbor Laboratory Press Voltage-Gated Calcium Channels Table 1. Subunit composition and function of Ca2þ channel types Ca2þ current a1 Specific type Subunits blocker Principal physiological functions Inherited diseases LCav1.1 DHPs Excitation-contraction coupling in Hypokalemic periodic skeletal muscle, regulation of paralysis transcription Cav1.2 DHPs Excitation-contraction coupling in Timothy syndrome: cardiac cardiac and smooth muscle, arrhythmia with endocrine secretion, neuronal developmental Ca2þ transients in cell bodies and abnormalites and autism dendrites, regulation of enzyme spectrum disorders activity, regulation of transcription Cav1.3 DHPs Endocrine secretion, cardiac pacemaking, neuronal Ca2þ transients in cell bodies and dendrites, auditory transduction Cav1.4 DHPs Visual transduction Stationary night blindness NCav2.1 v-CTx-GVIA Neurotransmitter release, Dendritic Ca2þ transients P/QCav2.2 v-Agatoxin Neurotransmitter release, Familial hemiplegic migraine, Dendritic Ca2þ transients cerebellar ataxia RCav2.3 SNX-482 Neurotransmitter release, Dendritic Ca2þ transients TCav3.1 None Pacemaking and repetitive firing Cav3.2 Pacemaking and repetitive firing Absence seizures Cav3.3 Abbreviations: DHP,dihydropyridine; v-CTx-GVIA, v-conotoxin GVIA from the cone snail Conus geographus; SNX-482, a synthetic version of a peptide toxin from the tarantula Hysterocrates gigas. 1988). L-type Ca2þ currents are also recorded in membrane potentials, inactivated rapidly, deac- endocrine cells where they initiate release of hor- tivated slowly, had small single channel con- mones (Yang and Berggren 2006) and in neurons ductance, and were insensitive to conventional where they are important in regulation of gene Ca2þ antagonist drugs available at that time expression, integration of synaptic input, and (Table 1). They were designated low-voltage- initiation of neurotransmitter release at special- activated Ca2þ currents for their negative volt- ized ribbon synapses in sensory cells (Tsien age dependence (Carbone and Lux 1984) or et al. 1988; Bean 1989a; Flavell and Greenberg T-type Ca2þ currents for their transient open- 2008). L-type Ca2þ currents are subject to regu- ings (Nowycky et al. 1985). lation by second messenger–activated protein Whole-cell voltage clamp and single- phosphorylation in several cell types as discussed channel recording from dissociated dorsal root below. ganglion neurons revealed an additional Ca2þ Electrophysiological studies of Ca2þ cur- current, N-type (Table 1) (Nowycky et al. rents in starfish eggs (Hagiwara et al. 1975) first 1985). N-type Ca2þ currents were initially revealed Ca2þ currents with different properties distinguished by their intermediate voltage de- from L-type, and these were subsequently char- pendence and rate of inactivation—more nega- acterized in detail in voltage-clamped dorsal tive and faster than L-type but more positive root ganglion neurons (Carbone and Lux and slower than T-type (Nowycky et al. 1985). 1984; Fedulova et al. 1985; Nowycky et al. They are insensitive to organic L-type Ca2þ 1985). In comparison to L-type, these novel channel blockers but blocked by the cone snail Ca2þ currents activated at much more negative peptide v-conotoxin GVIA and related peptide Cite this article as Cold Spring Harb Perspect Biol 2011;3:a003947 3 Downloaded from http://cshperspectives.cshlp.org/ on October 5, 2021 - Published by Cold Spring Harbor Laboratory Press W.A. Catterall toxins (Tsien et al. 1988; Olivera et al. 1994). MOLECULAR PROPERTIES OF Ca2þ This pharmacological profile has become the CHANNELS primary method to distinguish N-type
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