Sodium channel mutations in paramyotonia congenita uncouple inactivation from activation

Chahine, Mohamed; George, Alfred L.; Zhou, Ming; Ji, Songbai; Sun, Weijing; Barchi, Robert L.; Horn, Richard

doi:10.1016/0896-6273(94)90271-2

Cited by 323 publications

(348 citation statements)

References 47 publications

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“…The conventional CaPO4 transfection method was employed in the transfection of tsA 201 cells with recombinant DNAs, as reported previously (Chahine et al, 1994). In brief, tsA 201 cells growing in 100-mm tissue culture dishes at 30-50% confluence were transfected with 15 Ixg of each plasmid cDNA encoding hSkM1 wild-type (wt) or mutant sodium channels after the formation of precipitates with CaPO 4.…”

Section: Transfection Of Cdnas Into Tsa Cellsmentioning

confidence: 99%

“…All sequence verified mutants were assembled into the mammalian expression construct pRc/CMV-hSkM1. The mutations L1433R and R1448C were made previously (Chahine et al, 1994, Yang et al, 1994. The double mutant L1433R/R1448C was assembled by ligation of a 1.75-kb XmnI/Xbal fragment from pRc/CMV-R1448C containing the R1448C mutation into the corresponding restriction sites of the pRc/CMV-L1433R construct.…”

Section: Mutagenesismentioning

confidence: 99%

“…Site-directed mutagenesis experiments were performed using the pSELECT Mutagenesis System (Promega Corp., Madison, WI) as previously described (Chahine et al, 1994). Antisense mutagenic oligonucleotides were as follows: L1433Q/E/K, 5'-gatcaggtcagatt[g,c,t]ggcaaggcccacaat-3' (square brackets define mixed synthesis sites, mutagenic sequence is underlined); L1433A, 5'-gatcaggtcagaggc_, ggcaaggcccacaat-3'; L1433M, 5'-gatcaggtcagacatggcaaggcccac-3'.…”

Section: Mutagenesismentioning

confidence: 99%

“…Although these mutations are spread throughout repeat domains D2 to D4, all that have been expressed (Chahine et al, 1994;Cannon and Strittmatter, 1993;Cummins et al, 1993;Yang et al, 1994) have profound effects on sodium channel inactivation, suggesting that multiple regions of the channel structure are involved in normal inactivation. The mechanisms by which each mutation affects inactivation, and the responsible properties of the amino acid side chain, in most cases remain to be determined.…”

Section: Introductionmentioning

confidence: 99%

“…The slowing of inactivation that is characteristic of PC mutations is distinguishable from the appearance of an abnormal slow gating mode reported in HYPP mutations. At the single-channel level, R1448C/H mutations inactivate poorly, with a greatly reduced rate constant for inactivation from the open state (Chahine et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

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Paramyotonia congenita mutations reveal different roles for segments S3 and S4 of domain D4 in hSkM1 sodium channel gating.

George

Horn

et al. 1996

The Journal of General Physiology

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Mutations in the gene encoding the voltage-gated sodium channel of skeletal muscle (SkM1) have been identified in a group of autosomal dominant diseases, characterized by abnormalities of the sarcolemmal excitability, that include paramyotonia congenita (PC) and hyperkalemic periodic paralysis (HYPP). We previously reported that PC mutations cause in common a slowing of inactivation in the human SkM1 sodium channel. In this investigation, we examined the molecular mechanisms responsible for the effects of L1433R, located in D4/$3, on channel gating by creating a series of additional mutations at the 1433 site. Unlike the R1448C mutation, found in D4/$4, which produces its effects largely due to the loss of the positive charge, change of the hydropathy of the side chain rather than charge is the primary factor mediating the effects of L1433R. These two mutations also differ in their effects on recovery from inactivation, conditioned inactivation, and steady state inactivation of the hSkM1 channels. We constructed a double mutation containing both L1433R and R1448C. The double mutation closely resembled R1448C with respect to alterations in the kinetics of inactivation during depolarization and voltage dependence, but was indistinguishable from L1433R in the kinetics of recovery from inactivation and steady state inactivation. No additive effects were seen, suggesting that these two segments interact during gating. In addition, we found that these mutations have different effects on the delay of recovery from inactivation and the kinetics of the tail currents, raising a question whether this delay is a reflection of the deactivation process. These results suggest that the $3 and $4 segments play distinct roles in different processes of hSkM1 channel gating: D4/$4 is critical for the deactivation and inactivation of the open channel while D4/$3 has a dominant role in the recovery of inactivated channels. However, these two segments interact during the entry to, and exit from, inactivation states.

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Section: Transfection Of Cdnas Into Tsa Cellsmentioning

confidence: 99%

Section: Mutagenesismentioning

confidence: 99%

Section: Mutagenesismentioning

confidence: 99%