CONOTOXINS

Toxins from cone shells ( Conus spp). The a -conotoxins (small peptides, 13-18 residues) are competitive inhibitors of nicotinic acetylcholine receptors. The m -conotoxins are small (22-residue) peptides that bind voltage-sensitive sodium channels in muscle, causing paralysis. The w -conotoxins are similar in size and inhibit voltage-gated calcium channels, thereby blocking synaptic transmission.