Gating-modifier toxin that reversibly and voltage-independently inhibits human Nav1.1/SCN1A and Nav1.7/SCN9A (IC(50)=111 nM) (PubMed:25754331). It also shows moderate inhibition on Nav1.2/SCN2A (1 uM inhibits current by 55%), Nav1.6/SCN8A (31%), Nav1.3/SCN5A (27%) and Nav1.4/SCN4A (23%) (PubMed:25754331). This toxin inhibits Nav1.7/SCN9A by interacting with the S3b-S4 paddle motif in channel domain II (PubMed:25754331). Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Monoisotopic mass. Does not inhibit Nav1.5/SCN5A, Nav1.8/SCN10A, and presumably not Nav1.9/SCN11A voltage-gated sodium channels. Belongs to the neurotoxin 10 (Hwtx-1) family. 22 (Htx-4) subfamily.