Beta toxins bind voltage-independently at site-4 of sodium channels (Nav) and shift the voltage of activation toward more negative potentials thereby affecting sodium channel activation and promoting spontaneous and repetitive firing. This toxin is lethal to crustaceans (freshwater crayfish (Cambarellus montezumae spp.)), it provokes a reversible paralysis to insects (crickets (Achaeta spp.)), but is not toxic to mice. At high concentrations, it does displace the (beta) mammal-specific toxin Cn2 from rat brain synaptosomes. Expressed by the venom gland. Has the structural arrangement of an alpha-helix connected to antiparallel beta-sheets by disulfide bonds (CS-alpha/beta). LD(50) is 28.5 mg/g body weight of crayfish. Belongs to the long (4 C-C) scorpion toxin superfamily. Sodium channel inhibitor family. Beta subfamily.