Alpha toxins bind voltage-independently at site-3 of sodium channels (Nav) and inhibit the inactivation of the activated channels, thereby blocking neuronal transmission (PubMed:2536799, PubMed:15249424, PubMed:15051403). This synthetic toxin inhibits inactivation of rat Nav1.4/SCN4A (when tested at 201 nM) (PubMed:27244051). In addition, it has been shown to cause a persistent sodium channel activation in nitrergic inhibitory fibers innervating the rabbit corpus cavernosum, resulting in NO release and cavernosal smooth muscle relaxation (PubMed:12551849). This toxin is active against mammals (PubMed:2536799, PubMed:15249424, PubMed:15051403). Expressed by the venom gland. Has the structural arrangement of an alpha-helix connected to antiparallel beta-sheets by disulfide bonds (CS-alpha/beta). Belongs to the long (4 C-C) scorpion toxin superfamily. Sodium channel inhibitor family. Alpha subfamily. The longest forms Tityustoxin V (also called Ts V and Ts3(1-66)) and Ts3(1-67) and the shortest form Tityustoxin III (also called Ts III and Ts3(1-62)) show minimal effect on Nav1.4/SCN4A, suggesting that the wild-type toxin corresponds to the amidated 64-residues long peptide (PubMed:8143874, PubMed:27244051).