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 compete with high affinity with 125I-Css4 bound on rat brain synaptosome and may bind with high affinity to Nav1.1/SCN1A, Nav1.2/SCN2A and Nav1.6/SCN8A. 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(100) is 4 ug/kg by intracranial injection into mice. Belongs to the long (4 C-C) scorpion toxin superfamily. Sodium channel inhibitor family. Beta subfamily.