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NaV 1.4

The voltage-gated sodium channel of skeletal muscle, NaV1.4 encoded bySCN4A, is composed of four highly homologous domains (DI–DIV) each consisting of six transmembrane segments (S1–S6). When inserted in membrane, the four domains of the protein fold to generate a central pore whereby the S5–S6 loops form the ion-selective pore. The S4 segments contain positively charged residues conferring voltage dependence to the protein. Domains are connected by intracellular loops; one of them, the DIII−DIV linker, contains the inactivation particle of the channel. The sketch gives an overview of locations of disease-associated missense variants in NaV1.4. Different colors indicate resulting diseases such as potassium-aggravated myotonia (PAM), paramyotonia congenita (PMC), hyperkalemic periodic paralysis (hyperPP), hypokalemic periodic paralysis (hypoPP type 2), and normokalemic periodic paralysis (normoPP, type 2).

Modified from Jurkat-Rott et al [2010]