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Voltage-gated sodium channels in the mammalian CNS initiate and propagate action potentials when excitatory inputs achieve threshold membrane depolarization. There are multiple sodium channel isoforms expressed in rat brain (types I, II, III, 6, and NaG). We have constructed a full-length cDNA clone encoding type I and compared the electrophysiological properties of type I (Rat1) and II (Rat2) channels in the absence and presence of the two accessory subunits beta1 and beta2. Injection into Xenopus oocytes of RNA encoding Rat1 resulted in functional sodium currents that were blocked by tetrodotoxin, with Kapp = 9.6 nM. Rat1 sodium channels had a slower time course of fast inactivation than Rat2. Coexpression of beta1 accelerated inactivation of both Rat1 and Rat2, resulting in comparable inactivation kinetics. Rat1 recovered from fast inactivation more rapidly than Rat2, regardless of whether beta1 or beta2 was present. The voltage dependence of activation was similar for Rat1 and Rat2 without the beta subunits, but it was more positive for Rat1 when beta1 and beta2 were coexpressed. The voltage dependence of inactivation was more positive for Rat1 than for Rat2, and coexpression with beta1 and beta2 accentuated that difference. Finally, sodium current amplitudes were reduced by 7-9% for both Rat1 and Rat2 channels when protein kinase A phosphorylation was induced. It has been suggested previously that Rat1 and Rat6 channels mediate transient and maintained sodium conductances, respectively, in Purkinje cells, and the electrophysiological properties of Rat1 currents are consistent with a role for this channel in mediating the rapidly inactivating, transient current.
Auld,
A rat brain Na+ channel alpha subunit with novel gating properties.
1988, Pubmed,
Xenbase
Auld,
A rat brain Na+ channel alpha subunit with novel gating properties.
1988,
Pubmed
,
Xenbase Beckh,
Differential regulation of three sodium channel messenger RNAs in the rat central nervous system during development.
1989,
Pubmed Black,
Sodium channel mRNAs I, II and III in the CNS: cell-specific expression.
1994,
Pubmed Burgess,
Mutation of a new sodium channel gene, Scn8a, in the mouse mutant 'motor endplate disease'.
1995,
Pubmed Cantrell,
Dopaminergic modulation of sodium current in hippocampal neurons via cAMP-dependent phosphorylation of specific sites in the sodium channel alpha subunit.
1997,
Pubmed
,
Xenbase Crill,
Persistent sodium current in mammalian central neurons.
1996,
Pubmed Dierks,
DNA sequences preceding the rabbit beta-globin gene are required for formation in mouse L cells of beta-globin RNA with the correct 5' terminus.
1981,
Pubmed Felts,
Sodium channel alpha-subunit mRNAs I, II, III, NaG, Na6 and hNE (PN1): different expression patterns in developing rat nervous system.
1997,
Pubmed Furuyama,
Distribution of I, II and III subtypes of voltage-sensitive Na+ channel mRNA in the rat brain.
1993,
Pubmed Gautron,
The glial voltage-gated sodium channel: cell- and tissue-specific mRNA expression.
1992,
Pubmed Gershon,
Protein kinase A reduces voltage-dependent Na+ current in Xenopus oocytes.
1992,
Pubmed
,
Xenbase Goldin,
Expression of ion channels by injection of mRNA into Xenopus oocytes.
1991,
Pubmed
,
Xenbase Gordon,
Tissue-specific expression of the RI and RII sodium channel subtypes.
1987,
Pubmed Hartshorne,
The sodium channel from rat brain. Purification and subunit composition.
1984,
Pubmed Isom,
Primary structure and functional expression of the beta 1 subunit of the rat brain sodium channel.
1992,
Pubmed
,
Xenbase Isom,
Structure and function of the beta 2 subunit of brain sodium channels, a transmembrane glycoprotein with a CAM motif.
1995,
Pubmed
,
Xenbase Joho,
Toxin and kinetic profile of rat brain type III sodium channels expressed in Xenopus oocytes.
1990,
Pubmed
,
Xenbase Kayano,
Primary structure of rat brain sodium channel III deduced from the cDNA sequence.
1988,
Pubmed Kohrman,
Insertional mutation of the motor endplate disease (med) locus on mouse chromosome 15.
1995,
Pubmed Kohrman,
A missense mutation in the sodium channel Scn8a is responsible for cerebellar ataxia in the mouse mutant jolting.
1996,
Pubmed Kontis,
Sodium channel activation gating is affected by substitutions of voltage sensor positive charges in all four domains.
1997,
Pubmed
,
Xenbase Li,
Convergent regulation of sodium channels by protein kinase C and cAMP-dependent protein kinase.
1993,
Pubmed Li,
Functional modulation of brain sodium channels by cAMP-dependent phosphorylation.
1992,
Pubmed Llinás,
Electrophysiological properties of in vitro Purkinje cell somata in mammalian cerebellar slices.
1980,
Pubmed Llinás,
The intrinsic electrophysiological properties of mammalian neurons: insights into central nervous system function.
1988,
Pubmed Noda,
Existence of distinct sodium channel messenger RNAs in rat brain.
,
Pubmed Noda,
Expression of functional sodium channels from cloned cDNA.
,
Pubmed
,
Xenbase Patton,
The adult rat brain beta 1 subunit modifies activation and inactivation gating of multiple sodium channel alpha subunits.
1994,
Pubmed
,
Xenbase Patton,
A voltage-dependent gating transition induces use-dependent block by tetrodotoxin of rat IIA sodium channels expressed in Xenopus oocytes.
1991,
Pubmed
,
Xenbase Raman,
Altered subthreshold sodium currents and disrupted firing patterns in Purkinje neurons of Scn8a mutant mice.
1997,
Pubmed Raman,
Resurgent sodium current and action potential formation in dissociated cerebellar Purkinje neurons.
1997,
Pubmed Schaller,
A novel, abundant sodium channel expressed in neurons and glia.
1995,
Pubmed Schiffmann,
Dopamine D1 receptor modulates the voltage-gated sodium current in rat striatal neurones through a protein kinase A.
1995,
Pubmed Smith,
Phosphorylation of brain sodium channels in the I--II linker modulates channel function in Xenopus oocytes.
1996,
Pubmed
,
Xenbase Smith,
Phosphorylation at a single site in the rat brain sodium channel is necessary and sufficient for current reduction by protein kinase A.
1997,
Pubmed
,
Xenbase Taglialatela,
Novel voltage clamp to record small, fast currents from ion channels expressed in Xenopus oocytes.
1992,
Pubmed
,
Xenbase Taylor,
Na+ currents that fail to inactivate.
1993,
Pubmed Vega-Saenz de Miera,
Molecular characterization of the sodium channel subunits expressed in mammalian cerebellar Purkinje cells.
1997,
Pubmed Westenbroek,
Differential subcellular localization of the RI and RII Na+ channel subtypes in central neurons.
1989,
Pubmed
