Iota-conotoxins bind to voltage-gated sodium channels (Nav) and act as agonists by shifting the voltage-dependence of activation to more hyperpolarized levels (By similarity). Causes circular motion, convulsions, copious urination, rigid paralysis and death upon intracranial injection into mice. Causes unbalanced swimming, swimming in diagonal and vertical motion and death, when injected intraperitoneally into goldfish. L-Leu and D-Leu forms are active on both nerve and muscle. Expressed by the venom duct. The cysteine framework is XI (C-C-CC-CC-C-C). The natural D-Leu form of the peptide is more potent than the synthetic L-Leu form. With hydroxyPro. Belongs to the conotoxin I1 superfamily.