Structure of conkunitzin-S1, a neurotoxin and Kunitz-fold disulfide variant from cone snail.

Cone snails (Conus) are predatory marine mollusks that immobilize prey with venom containing 50-200 neurotoxic polypeptides. Most of these polypeptides are small disulfide-rich conotoxins that can be classified into families according to their respective ion-channel targets and patterns of cysteine-cysteine disulfides. Conkunitzin-S1, a potassium-channel pore-blocking toxin isolated from C.

Structure of a novel P-superfamily spasmodic conotoxin reveals an inhibitory cystine knot motif.

Conotoxin gm9a, a putative 27-residue polypeptide encoded by Conus gloriamaris, was recently identified as a homologue of the "spasmodic peptide", tx9a, isolated from the venom of the mollusk-hunting cone shell Conus textile (Lirazan, M. B., Hooper, D.