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conotoxin
A conotoxin is one of a group of neurotoxic peptides isolated from the venom of the marine cone snail, genus ''Conus''. Conotoxins, which are peptides consisting of 10 to 30 amino acid residues, typically have one or more disulfide bonds. Conotoxins have a variety of mechanisms of actions, most of which have not been determined. However, it appears that many of these peptides modulate the activity of ion channels. Over the last few decades conotoxins have been subject of pharmacological interest. == Hypervariability ==
Conotoxins are hypervariable even within the same species; the genes that encode them do not act endogenously, and thus are less conserved and more likely to experience gene duplication events and nonsynonymous mutations which lead to the development of novel functions. These genes will experience less selection against mutations, and therefore mutations will remain in the genome longer, allowing more time for potentially beneficial novel functions to arise. Variability in conotoxin components reduces the likelihood that prey organisms will develop resistance; thus cone snails are under constant selective pressure to maintain polymorphism in these genes because failing to evolve and adapt will lead to extinction (''Red Queen hypothesis'').
抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「conotoxin」の詳細全文を読む
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