TY - JOUR
T1 - Chemical and electrophysiological characterization of new peptide neurotoxins from the venom of the molluscivorous snail conus textile neovicarius
T2 - A review
AU - Spira, M. E.
AU - Hasson, A.
AU - Fainzilber, M.
AU - Gordon, D.
AU - Zlotkin, E.
PY - 1993
Y1 - 1993
N2 - 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 spontaneous repetitive firing. The TxI toxins also induced a marked prolongation of the action potential duration. Voltage clamp experiments revealed that the TxI toxins alter the kinetics of the sodium current either by slowing down the rate of sodium current inactivation, or by recruiting silent sodium channels with slower activation and inactivation kinetics. The toxins shift the voltage-dependent steady-state Na+ current inactivation curve to more positive values by 6 mV. These changes are not associated with alteration in the rate of I(Na)+ activation, in the peak I,(Na)+, or the sodium current reversal potential. TxI represents a new class of conotoxins with an unusual phylogenic specificity and may therefore be useful as a probe for the study of voltage gated sodium channels. (This review summarizes previously published papers).
AB - 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 spontaneous repetitive firing. The TxI toxins also induced a marked prolongation of the action potential duration. Voltage clamp experiments revealed that the TxI toxins alter the kinetics of the sodium current either by slowing down the rate of sodium current inactivation, or by recruiting silent sodium channels with slower activation and inactivation kinetics. The toxins shift the voltage-dependent steady-state Na+ current inactivation curve to more positive values by 6 mV. These changes are not associated with alteration in the rate of I(Na)+ activation, in the peak I,(Na)+, or the sodium current reversal potential. TxI represents a new class of conotoxins with an unusual phylogenic specificity and may therefore be useful as a probe for the study of voltage gated sodium channels. (This review summarizes previously published papers).
KW - Brain
KW - Conotoxin
KW - Cultured neurons
KW - Sodium currents
KW - Sodium inactivation
UR - http://www.scopus.com/inward/record.url?scp=0027292317&partnerID=8YFLogxK
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.systematicreview???
C2 - 8225942
AN - SCOPUS:0027292317
SN - 0021-2180
VL - 29
SP - 530
EP - 543
JO - Israel Journal of Medical Sciences
JF - Israel Journal of Medical Sciences
IS - 9
ER -