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). Produces excitatory symptoms when injected intracranially into mice and is lethal at higher doses. Exposure to frog cutaneous pectoris induces spontaneous and repetitive action potentials. This effect is slowly reversible. Natural peptide (with D-Phe) is active on nerve, but not on muscle. Synthetic peptide (with L-Phe) is not 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-Phe form of the peptide is more potent than the synthetic L-Phe form. Belongs to the conotoxin I1 superfamily.