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QuickView for Voltage gated sodium channel, alpha-1 subunit (biogroup)
- Description:
- Voltage-dependent sodium channels are transmembrane (TM) proteinsresponsible for the depolarising phase of the action potential in mostelectrically excitable cells. They may exist in 3 states: theresting state, where the channel is closed; the activated state, where thechannel is open; and the inactivated state, where the channel is closedand refractory to opening. Several different structurally and functionallydistinct isoforms are found in mammals, coded for by a multigene family, these being responsible for the different types of sodium ion currentsfound in excitable tissues.The structure of sodium channels is based on 4 internal repeats of a 6-helixbundle (in which 5 of the membrane-spanning segments are hydrophobic andthe other is positively charged), forming a 24-helical bundle. The chargedsegments are believed to be localised within clusters formed by their 5 hydrophobic neighbours: it is postulated that the charged domain may be thevoltage sensor region, possibly moving outward on depolarisation, causing aconformational change. This model contrastswith another, in which the TM segments are juxtaposedoctagonally. The basic structural motif (the 6-helix bundle) is also found in potassium and calcium channel alpha subunits.The SCN1A gene encodes the NaB1 channel and is particularly expressed inthe brain, but is also found in a variety of other tissues, ranging from theretina to the olfactory bulb. Epilepsy, a disorder of neuronalhyperexcitability, has been associated with altered kinetics of SCN1A, aswell as delayed inactivation of SCN2A.This entry represents the alpha 1 subunits of the voltage-gated Na+ channel superfamily. For entries containing other members of this superfamily , , .
- Taxonomy/Path:
- InterPro : Voltage gated sodium channel, alpha subunit / Voltage gated sodium channel, alpha-1 subunit
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