Highly potent toxin against insect sodium channel (Nav) and with less potent activity against mammalian sodium channels (PubMed:29567943). Potently inhibits inactivation of insect sodium channels of B.germanica (BgNav1) (EC(50)=8.6 nM), D.melanogaster (DmNav1), and arachnid sodium channel V.destructor (VdNav1) (PubMed:29567943, PubMed:34445875). Also delays the inactivation of most mammalian Nav channels tested (hNav1.1/SCN1A; EC(50)=124.1 nM, rNav1.2/SCN2A; EC(50)=359.6 nM, rNav1.3/SCN3A; EC(50)=135.4 nM, rNav1.4/SCN4A; EC(50)=145.5 nM, hNav1.5/SCN5A; EC(50)=138.3 nM, mNav1.6/SCN8A; EC(50)=240.4 nM, hNav1.9/SCN9A; EC(50)=76.5 nM) (PubMed:29567943, PubMed:34445875). 1 uM is enough to completely inhibits the inactivation, resulting in sustained non-inactivating currents (PubMed:29567943). In addition, the toxin significantly enhances the recovery from inactivation, and the open state is not required for the toxin to interact with the channel (PubMed:29567943). In vivo, injection into green crabs (Carcinus maenas at 1 mug/kg) of small doses (1-5 ug/kg) results in slow and fast permanent paralysis, whereas injection of high doses (more than 10 ug/kg) causes death (PubMed:29567943). Injection into juvenile Blaptica dubia cockroaches results in death or permanent paralysis at doses higher than 7.1 ug/kg (PubMed:29567943). Injection into brine shrimp (Artemia salina) stops movement or causes death after 24 hours (EC(50)=0.3 uM) (PubMed:34445875). In the rare inherited cardiac arrhythmia Brugada syndrome 1 (BRGDA1), this toxin is able to restore the loss of function by reducing channel inactivation, without affecting activation, by binding to Nav1.5/SCN5A (PubMed:32850980). Confined to the epidermis and to the mucus layer. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Does not shows effect on both human and rat Nav1.8/SCN10A. The primary and 3D structures of the mature peptide is identical to that of Nemertide alpha-1 from Lineus longissimus (AC P0DM24). Links to the 3D-structure (PDB=6ENA) is available in this entry. Belongs to the nemertide family.