Alpha toxins bind voltage-independently at site-3 of sodium channels (Nav) and inhibit the inactivation of the activated channels, thereby blocking neuronal transmission. This toxin inhibits inactivation of Nav1.4/SCN4A (EC(50)=2.23 uM) and drosophila DmNav1 (EC(50)=220 nM) (PubMed:21969612, Ref.2). The toxin (1 uM) does not significantly shift the midpoint of activation at the two channels, but induces a significant depolarizing shift in the V(1/2) of inactivation of the channels (PubMed:21969612). In addition, the toxin accelerates the recovery from fast inactivation in Nav1.4/SCN4A and DmNav1 (PubMed:21969612). It also shows antimicrobial activity (Ref.2). Expressed by the venom gland. Has the structural arrangement of an alpha-helix connected to antiparallel beta-sheets by disulfide bonds (CS-alpha/beta). Shows no effect on Nav1.2/SCN2A, Nav1.3/SCN3A, Nav1.5/SCN5A, Nav1.6/SCN8A, Nav1.7/SCN9A and Nav1.8/SCN10A (PubMed:21969612). Belongs to the long (4 C-C) scorpion toxin superfamily. Sodium channel inhibitor family. Alpha subfamily.