Vorlesungsskripte zoo physiology
Conotoxins - muscle poisons from cone snails
4. Five Conotoxin families
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The Conotoxin families |
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Primary structure of members of 5 conotoxin families. The toxins are grouped according to their common target proteins (receptors) in the body : a-Conotoxins bind to nicotinic acetylcholine receptors, m-Conotoxins to muscle-type Na+ channels, w-Conotoxins to neuronal N-type Ca2+ channels, d-Conotoxins at neuronal Na+ channels and k-Conotoxins to neuronal K+ channels. The specific disulphide framework (black lines) is indicative of the structure of each family.
Toxins from the venoms of predatory Conus are represented by Conus geographus and Conus purpurascens. |
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The structure of w- Conotoxin |
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Structural model of an w-Conotoxin from the venom of Conus geographus.
The individual amino acid residues are indicated by the single letter codes (symbol O: Hydroxyproline). Disulphide bridges between two Cysteine residues (symbol C) are represented by black bars. The disulphide bridges strengthen the regional structure of these small peptides and are essential for biological activity.
Most Conotoxins are small peptides (10 to 30 amino acids). Probably the most important advantage of this small size is that the Toxin molecules can diffuse fast in the body of the target animals to produce a more rapid paralysis.
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Edited by Bruce Livett (10 January 2000, with permission) using Word7, from a Babel Fish electronic web translation
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Institute for biological data processing in the research center Juelich