MuO-conotoxins are gating-modifier toxins that inhibit sodium current by trapping the domain II voltage sensor in the closed position to prevent opening of the sodium channel. This toxin inhibits rNav1.2/SCN2A (IC(50)=532 nM), rNav1.4/SCN4A (IC(50)=438 nM) and rNav1.7/SCN9A (IC(50)=345 nM) (PubMed:10627583). It blocks Nav channels by interacting mainly with the C-terminal part of the pore loop of domain-3 (PubMed:16458302). It does not bind on site 1 (PubMed:8890263). At small concentration, this toxin also acts as a calcium current agonist, whereas at higher doses it blocks fast-inactivating calcium current (PubMed:7727394). Expressed by the venom duct. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. The cysteine framework is VI/VII (C-C-CC-C-C). Belongs to the conotoxin O1 superfamily.