Key result
The DIIIS4 R3C mutation selectively alters gating charge movement and its remobilization at hyperpolarized membrane potentials, furthering understanding of hypokalemic periodic paralysis.
The DIIIS4 R3C mutation alters gating charge movement at hyperpolarized potentials, providing mechanistic insight into sodium channel defects in hypokalemic periodic paralysis.
Heterologous expression of sodium channel mutations in hypokalemic periodic paralysis reveals 2 variants on channel dysfunction. Charge-reducing mutations of voltage sensing S4 arginine residues alter channel gating as typically studied with expression in mammalian cells. These mutations also produce leak currents through the voltage sensor module, as typically studied with expression in Xenopus oocytes. DIIIS4 mutations at R3 in the skeletal muscle sodium channel produce gating defects and omega current consistent with the phenotype of reduced excitability. Here, we confirm DIIIS4 R3C gating defects in the oocyte expression system for fast inactivation and its recovery. We provide novel data for the effects of the cysteine mutation on voltage sensor movement, to further our understanding of sodium channel defects in hypokalemic periodic paralysis. Gating charge movement and its remobilization are selectively altered by the mutation at hyperpolarized membrane potential, as expected with reduced serum potassium.
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Groome et al. (2014) studied Hypokalemic periodic paralysis. DIIIS4 R3C mutation was evaluated on Gating charge movement and remobilization. The DIIIS4 R3C mutation selectively alters gating charge movement and its remobilization at hyperpolarized membrane potentials, furthering understanding of hypokalemic periodic paralysis.
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