8.B.1.2.2
Beta-anti-mammalian scorpian toxin, Css4 of 87 aas and 1 N-terminal TMS.  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 (Cestèle et al. 2001). This toxin is active only on Na⁺ channels in mammals (Cestèle et al. 1998). Binding results from electrostatic interactions in domain II of the Na⁺ channels (Mantegazza and Cestèle 2005).