Potent and selective inhibitor of hNav1.7/SCN9A (IC(50)=610 nM) (PubMed:29393892). Also shows a weak activity towards Nav1.3/SCN3A (IC(50)=7950 nM) (PubMed:29393892). In addition, inhibits voltage-gated potassium channels (Kv) in rat DRG neurons (PubMed:18581053). It does not alter the voltage dependence of activation, but it causes a small hyperpolarizing shift in the steady-state inactivations of Nav1.7/SNC9A (PubMed:29393892). Chimera experiments show that the toxin binds to the DIIS3-S4 linker (site 4) of Nav1.7/SCN9A, whereas Nav1.7/SCN9A Asp-827 residue is shown by substitution experiments to be critical for its sensitivity (PubMed:19463735, PubMed:29393892). The toxin traps the domain II voltage sensor in the closed configuration, and not in an outward position (PubMed:29393892). In vivo, shows analgesic activity in three rodent pain models (formalin-induced, acid-induced, and thermal) (PubMed:29393892). Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Monoisotopic mass. Is a promising lead molecule for the development of novel therapeutics in the treatment of pain. Does not inhibit TTX-resistant sodium currents on rat dorsal root ganglion (DRG) neurons (PubMed:18581053, PubMed:19463735, PubMed:29393892). Has no activity on voltage-gated potassium channel Kv2.1/KCNB1 expressed in frog oocytes (PubMed:19463735). Does not show activity towards Nav1.1/SCN1A, Nav1.2/SCN2A, Nav1.4/SCN4A, Nav1.5/SCN5A, Nav1.6/SCN8A, Nav1.8/SCN10A sodium channel (PubMed:29393892). Belongs to the neurotoxin 10 (Hwtx-1) family. 39 (Jztx-34) subfamily.