Potent voltage-gated sodium channel blocker (IC(50)=190 nM and 210 nM on human and rat Nav1.3/SCN3A respectively, 430 nM on human Nav1.7/SCN9A, 770 nM and 290 nM on human and rat Nav1.8/SCN10A, respectively) (By similarity). Binds the voltage-sensor domain of the potassium channel KvAP (from Aeropyrum pernix) and weakly inhibits this channel (PubMed:15287735). Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Shows only a very weak inhibition on human Nav1.5/SCN5A. The primary structure of the mature peptide is identical to that of VSTX3 from Paraphysa scrofa (AC P0DL74). Belongs to the neurotoxin 10 (Hwtx-1) family. 61 (VSTX3) subfamily.