Voltage-sensor movements describe slow inactivation of voltage-gated sodium channels II: a periodic paralysis mutation in Na(V)1.4 (L689I) Journal Article

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Authors: Silva, J. R.; Goldstein, S. A.
Article Title: Voltage-sensor movements describe slow inactivation of voltage-gated sodium channels II: a periodic paralysis mutation in Na(V)1.4 (L689I)
Abstract: In skeletal muscle, slow inactivation (SI) of Na(V)1.4 voltage-gated sodium channels prevents spontaneous depolarization and fatigue. Inherited mutations in Na(V)1.4 that impair SI disrupt activity-induced regulation of channel availability and predispose patients to hyperkalemic periodic paralysis. In our companion paper in this issue (Silva and Goldstein. 2013. J. Gen. Physiol. http://dx.doi.org/10.1085/jgp.201210909), the four voltage sensors in Na(V)1.4 responsible for activation of channels over microseconds are shown to slowly immobilize over 1-160 s as SI develops and to regain mobility on recovery from SI. Individual sensor movements assessed via attached fluorescent probes are nonidentical in their voltage dependence, time course, and magnitude: DI and DII track SI onset, and DIII appears to reflect SI recovery. A causal link was inferred by tetrodotoxin (TTX) suppression of both SI onset and immobilization of DI and DII sensors. Here, the association of slow sensor immobilization and SI is verified by study of Na(V)1.4 channels with a hyperkalemic periodic paralysis mutation; L689I produces complex changes in SI, and these are found to manifest directly in altered sensor movements. L689I removes a component of SI with an intermediate time constant (~10 s); the mutation also impedes immobilization of the DI and DII sensors over the same time domain in support of direct mechanistic linkage. A model that recapitulates SI attributes responsibility for intermediate SI to DI and DII (10 s) and a slow component to DIII (100 s), which accounts for residual SI, not impeded by L689I or TTX.
Journal Title: The Journal of general physiology
Volume: 141
Issue: 3
ISSN: 1540-7748; 0022-1295
Publisher: Unknown  
Journal Place: United States
Date Published: 2013
Start Page: 323
End Page: 334
Language: eng
DOI/URL:

10.1085/jgp.201210910
Notes: LR: 20161019; GR: R01 NS058505/NS/NINDS NIH HHS/United States; GR: 5T32HL007237/HL/NHLBI NIH HHS/United States; GR: R01NS058505/NS/NINDS NIH HHS/United States; GR: T32 HL007237/HL/NHLBI NIH HHS/United States; GR: R01 HL105949/HL/NHLBI NIH HHS/United States; JID: 2985110R; 0 (Muscle Proteins); 0 (NAV1.4 Voltage-Gated Sodium Channel); OID: NLM: PMC3581693; ppublish