Potently and reversibly inhibits some human voltage-gated sodium channels (Nav1.1/SCN1A (IC(50)=72.0 nM), Nav1.2/SCN2A (IC(50)=75.5 nM), Nav1.6/SCN8A (IC(50)=115.0 nM), Nav1.7/SCN9A (IC(50)=52.7-129.5 nM), Nav1.3/SCN3A (IC(50)=306.6 nM)) (PubMed:30784059). The hNav1.7/SCN9A channel inhibition occurs without any change in steady-state inactivation- and conductance-voltage relationships (PubMed:30784059). On adult mouse DRG neurons, this toxin is approximately 1000-fold more efficient to inhibit tetrodotoxin (TTX)-sensitive than TTX-resistant sodium currents (PubMed:30784059). In vivo, this toxin exhibits analgesic effects in mice pain models (PubMed:30784059). Monomer. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. LD(50) is 144.4 nmol/kg by intramuscular injection within 1 hr. Shows low or no activity on hNav1.4/SCN4A (IC(50)=7.7 uM), hNav1.5/SCN5A (IC(50)>10 uM), hNav1.8/SCN10A (IC(50)>10 uM), hCav1.2/CACNA1C, hCav3.1/CACNA1G, hCav3.2CACNA1H, hKv7.1/KCNQ1, Kv11.1/KCNH2/ERG1, and hKir2.1/KCNJ2/IRK1 channels. Belongs to the neurotoxin 10 (Hwtx-1) family. 14 (Hntx-1) subfamily.