Potent inhibitor of Nav1.2/SCN2A voltage-gated sodium channels (IC(50)=0.6-0.7 nM) (PubMed:16267209, PubMed:29703751). Also weakly inhibits Nav1.1/SCN1A, Nav1.4/SCN4A, Nav1.5/SCN5A, Nav1.7/SCN9A and Nav1.8/SCN10A (IC(50)=20-610 nM) (PubMed:16267209, PubMed:29703751). It acts by shifting the voltage dependence of channel activation to more depolarized potentials and by blocking the inward component of the sodium current (PubMed:16267209). It shows low affinity for lipid bilayers (PubMed:29703751). In vivo, this toxin causes general ataxia, lack of response to stimuli, and semiparalysis (PubMed:16267209). After a few minutes, the mice are unable to stand, and breathing is reduced in rhythm and intensity (PubMed:16267209). Symptoms gradually increase with progressive slowing of breathing and flaccid paralysis; death occurred within 10 to 20 minutes post injection (PubMed:16267209). Animals remain totally flaccid, and no symptoms of excitatory neurotoxicity are observed (PubMed:16267209). Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Belongs to the neurotoxin 10 (Hwtx-1) family. 08 (Gtx1-15) subfamily.