Conus geographus

Figure 15. Data from single channel experiments, plotted to show the relationship between kinetic and equilibrium parameters for several of the saxitoxins, tetrodotoxin, and Conus geographus toxin GIIIA. Compound numbering corresponds to that in Figure 1. The vertical axis is and the horizontal axis is dwell time, the reciprocal of k j. The dissociation constant, the ratio of k jj/k, therefore corresponds to distance along the diagonal. Data primarily from Ref. 95.

Conus. Thus, Figure 6c shows a group of fish-hunting cones, the Conus magus-striatus group. Other piscivorous species such as Conus geographus are less closely related to the species shown in Figure 6c. 

In the fish-hunting cone snail venoms, a- and w-conotoxins are ubiquitously distributed. As noted above, z-conotoxins have only been found in one species. Conus geographus. In addition to these three well-characterized classes, however, a fourth class of paralytic conotoxins has been found. In contrast to the a-, z-, and... 

Another potentially paralytic conotoxin was recently described this was a peptide purified from Conus geographus venom, which like / -conotoxin appeared to target to voltage-sensitive Na channels. However, the structure of "conotoxin GS" [nomenclature of Yanagawa et al. (J7)] was less homologous to / -conotoxins than to the w-conotoxins, which are Ca channel blockers. The same peptide was purified and characterized using a different assay, the induction of highly aberrant behavior upon ic injection of mice (L. J. Cruz, unpublished data). 

Figure 6 Venomous marine cone snails, (a) Geography cone Conus geographus (Public domain)) (b) Queen Victoria cone [Conus victoriae)-, (c) cloth of gold cone [Conus textile), (d) marble cone [Conus marmoreus (Public domain)) (e) closing view of proboscis with toxoglossan cone snail (f) microscope picture of toxoglossan from Conus consors. Photos (b), (c), (e),...

Conotoxins are small (10-30 amino acids), disulphide-rich, conformationally constrained peptides produced by marine mollusks such as cone snails. The fish-hunting snails, in particular Conus geographus, have been extensively studied. Depending upon the arrangement of disulphide bonds and the number of residues between cysteines, five or more classes of conotoxin can be structurally identified ... 

Olivera, . M., McIntosh, J. M., Lourdes, J. C., Luque, F. A., and Gray, W. R. (1984). Purification and sequence of a presynaptic peptide toxin from Conus geographus venom. Biochemistry 23, 5087-5090. 

Conus geographus peptide] (peptide) Conus geographus (sea gastropod) [venom] NMDA-Glu-R antagonist... 

Conopressins Lys-conopressin-G CFIRNCPKG Conus geographus p (L-type) Vasopressin... 

Gray, W. R., Luque, A., Olivera, B.M., Barrett, J., Cruz, L. J. Peptide toxins from Conus geographus venom. J. Biol. Chem. 1981, 256, 4734-4740... 

FIGU RE 5.1 Upper panel shows the sequence of CO-conotoxins isolated from Conus geographus (GVIA), Conus magus (MVllA, MVllC, and MVllD) and Conus Striatus (SVIA). Lower panel shows the arrangement of the cys residues that constitutes the four-loop structure. 

Marine snails belonging to the genus Conus are venomous predators that immobilize their prey by a highly specialized venom apparatus. The venom which is of proteinaceous or peptide nature is injected into the prey by means of a disposable hollow tooth which serves both as harpoon and hypodermic needle. A number of human fatalities have resulted from the sting of Conus geographus. 

Gray, W.R., A. Luque, B.M. Olivera, J. Barrett, and L.J. Cruz Peptide Toxins from Conus geographus Venom. J. Biol. Chem. 256, 4734 (1981). 

Stone, B.L., and W.R. Gray Occurrence of Hydroxyproline in a Toxin from the Marine Snail Conus geographus. Arch. Biochem. Biophys. 216, 765 (1982). 

Nakamura, H., J. Kobayashi, Y. Ohizumi, and Y. Hirata Isolation and Amino Acid Compositions of Geographutoxin I and II from the Marine Snail Conus geographus Linne. Experientia 39, 590 (1983). 

Clark, C., B.M. Olivera, and L.J. Cruz A Toxin from the Venom of the Marine Snail Conus geographus which Acts on the Vertebrate Central Nervous System. Toxi-con 19, 691 (1981). 

Olivera, B.M., J.M. McIntosh, C. Clark, D. Middlemas, W.R. Gray, and L.J. Cruz A Sleep-Inducing Peptide from Conus geographus Venom. Toxicon 23, 277 (1985). 

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