Open AccessMollusc‐specific toxins from the venom of Conus textile neovicarius
Author(s) -
FAINZILBER Michael,
GORDON Dalia,
HASSON Arik,
SPIRA Micha E.,
ZLOTKIN Eliahu
Publication year - 1991
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1991.tb16412.x
Subject(s) - venom , conotoxin , conus , biology , peptide , depolarization , sodium channel , aplysia , biochemistry , chemistry , biophysics , anatomy , sodium , neuroscience , organic chemistry
Three peptide toxins exhibiting strong paralytic activity to molluscs, but with no paralytic effects on arthropods or vertebrates, were purified from the venom of the molluscivorous snail Conus textile neovicarius from the Red Sea. The amino acid sequences of these mollusc specific toxins are: TxIA, WCKQSGEMCNLLDQNCCDGYCIVLVCT (identical to the so called ‘King Kong peptide’); TxIB, WCKQSGEMCNVLDQNCCDGYCIVFVCT; TxIIA, WGGYSTYCγVDSγCCSDNCVRSYCT (γ=γ‐carboxyglutamate). There is a similarity of the Cys framework of these toxins to that of the ω‐conotoxins; however, their net negative charges, high content of hydrophobic residues and uneven number of Cys residues in TxIIA, are highly unusual for conotoxins. When assayed on isolated cultured Aplysia neurons, all three toxins induced membrane depolarization and spontaneous repetitive firing. The TxI toxins also induce a marked prolongation of the action potential duration, which is sodium dependent. These effects differ significantly from the blocking activities of piscivorous venom conotoxins. These mollusc specific conotoxins may therefore serve as new and selective probes for ion‐channel functions in molluscan neuronal systems.