Conantokins inhibit N-methyl-D-aspartate (NMDA) receptors. This toxin is potent in the following order of preference: NR2B approximately NR2A/GRIN2A > NR2C/GRIN2C >> NR2D/GRIN2D. Induces sleep-like symptoms in young mice. Is a highly potent anticonvulsant compound. Divalent cations stabilize the toxin the in alpha-helix conformation. Zinc also stabilizes the alpha-helical conformation. Expressed by the venom duct. The cysteine framework is C-C. Exists in two forms, due to cis-trans isomerization at 106-Tyr-Pro-107. Belongs to the conotoxin B superfamily.