Conantokins inhibit N-methyl-D-aspartate (NMDA) receptors. This toxin has the highest potency for the NR2B/GRIN2B subunit, followed by NR2A/GRIN2A, NR2C/GRIN2C, and NR2D/GRIN2D subunits. Expressed by the venom duct. The cysteine framework is C-C. Adopts an alpha-helical conformation in presence and in absence of divalent cations. Calcium facilitates disulfide bond formation of the synthetic peptide. Belongs to the conotoxin B superfamily.