VOLUME 6 NUMBER 1 (January to June 2013)

by Elsie C. Jimenez

Department of Physical Sciences, College of Science, University of the PhilippinesBaguio, Baguio City 2600, Philippines

The cone snail (genus Conus) peptides known asconopeptides or conotoxins typically consist ofabout 10-50 amino acid (AA) residues. Thepeptides are processed from larger precursors withmany more AA residues. Different regions of thepeptide precursors (signal sequence, propeptide, mature peptide)have significantly diverged and are practically used as basis forthe classification of Conus peptides into superfamilies. Peptidesof a superfamily have highly homologous signal sequences andfew variable AA residues in propeptide regions. Generally, themature peptides (conopeptides) have relatively more variable AAresidues. Peptide diversity also occurs in members of the samesuperfamily that differ in their molecular targets or members ofdifferent superfamilies that have the same molecular target.Conotoxins are highly selective antagonists of ligand-gated andvoltage-gated ion channels. Consequently, they are used tocharacterize specific subtypes of receptors or ion channels. Thisoverview describes the structural and functional diversity ofconotoxins that influence neurotransmission through their actionon nicotinic acetylcholine receptors (nAChRs), to demonstratemolecular diversity in various classes of Conus peptides. Theprimary structures, cysteine patterns, disulfide bondingframeworks, physiological effects and target specificities aredescribed. The occurrence of these peptides in Conus venomsgives insights into the evolutionary tactics of cone snails. Theconotoxins are useful as tools for investigating the structure andphysiological roles of nAChRs. As the structural and functionaldiversity of conotoxins continues to be explored, these peptidescan possibly reveal important neuropharmacological applicationsand therapeutic potential.