Excitatory insect beta-toxins induce a spastic paralysis. They 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 shows an evident analgesic effect on mice, but is devoid of mammalian toxicity. Expressed by the venom gland. Belongs to the long (4 C-C) scorpion toxin superfamily. Sodium channel inhibitor family. Beta subfamily.