Mammal beta-toxins bind voltage-independently at site-4 of sodium channels (Nav) and shift the activation voltage to more negative potentials. This toxin is active against mammals. 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 20 ug/kg in mice. 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.