Beta toxins bind at site-4 of sodium channels and shift the voltage of activation toward more negative potentials thereby affecting sodium channel activation and promoting spontaneous and repetitive firing. This toxin is active against mammals and lethal to mice. Selectively modulates Nav1.4/SCN4A, a sodium channel present in both denervated and innervated skeletal muscle. Expressed by the venom gland. Has the structural arrangement of an alpha-helix connected to antiparallel beta-sheets by disulfide bonds (CS-alpha/beta). Is neutralized by the single-chain antibody fragment 10FG2. Belongs to the long (4 C-C) scorpion toxin superfamily. Sodium channel inhibitor family. Beta subfamily.