Inhibitor of voltage-gated potassium and sodium channels. Among other potassium channels, it selectively inhibits Kv10.1/KCNH1/EAG1 (IC(50)=236 nM) by shifting the voltage dependence of channel activation in a depolarising direction, it shows a maximum inhibition of 80% at saturating concentrations, it shows fast on-rates, and is poorly reversible. It also slightly affects channel inactivation, when the membrane is highly depolarised (>+80 mV). It shows similar potency on Nav1.7/SCN9A (IC(50)=222 nM) and lower potency on Nav1.2/SCN2A (IC(50)=519 nM). Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Monoisotopic mass. Could be used as informative lead for the development of novel antiepileptic drugs, as well as pharmacological tool for probing Kv10.1/KCNH1/EAG1 function. Weakly inhibits Nav1.5/SCN5A (IC(50)=2565), and Kv11.1/KCNH2/ERG1 (IC(50)=8197 nM). Belongs to the neurotoxin 10 (Hwtx-1) family.