Weakly blocks the rat SCN2A/SCN1B (Nav1.2/beta-1) sodium channel (IC(50)=68 uM) and the insect sodium channel para/tipE (IC(50)=4.3 uM), without altering the activation or inactivation kinetics (depressant toxin). Monomer. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Has no effect on mammalian SCN3A/SCN1B (Nav1.3/beta-1), SCN4A (Nav1.4), SCN5A/SCN1B (Nav1.5/beta-1), and SCN9A/SCN1B (Nav1.7/beta-1) (PubMed:14675784, PubMed:26429937). Has also no effect on sodium subtypes in rat DRG neurons containing Nav1.1/SCN1A, Nav1.6/SCN8A, Nav1.7/SCN9A, Nav1.8/SCN10A and Nav1.9/SCN11A (PubMed:14675784). Klint et al., 2015 worked with a recombinant peptide N-terminally extended by an Ala residue (AECKGFGKSCVPGKNECCSGYACNSRDKWCKVLL). Belongs to the neurotoxin 10 (Hwtx-1) family. 14 (Hntx-1) subfamily.