Conantokins inhibit N-methyl-D-aspartate (NMDA) receptors. This toxin has highest potency for the NR2B/GRIN2B subunit. It induces sleep in 10-day-old mice when injected intracranially, and hyperactivity in 24-day-old mice. Adopts alpha-helical conformations in the presence of divalent cations and is unstructured in the absence of divalent cations. Expressed by the venom duct. The mature peptide does not contain cysteine residue. Belongs to the conotoxin B superfamily.