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Title: Jingzhaotoxin-I, a novel spider neurotoxin preferentially inhibiting cardiac sodium channel inactivation
Authors: Xiao, Yucheng ×
Tang, Jianzhou
Hu, Weijun
Xie, Jinyun
Maertens, Chantal
Tytgat, Jan
Liang, Songping #
Issue Date: Apr-2005
Series Title: Journal of Biological Chemistry vol:280 issue:13 pages:12069-76
Abstract: Jingzhaotoxin-I (JZTX-I), a 33-residue polypeptide, is derived from the Chinese tarantula Chilobrachys jing-zhao venom based on its ability to evidently increase the strength and the rate of vertebrate heartbeats. The toxin has three disulfide bonds with the linkage of I-IV, II-V, and III-VI that is a typical pattern found in inhibitor cystine knot molecules. Its cDNA determined by rapid amplification of 3'- and 5'-cDNA ends encoded a 62-residue precursor with a small proregion of eight residues. Whole-cell configuration indicated that JZTX-I was a novel neurotoxin preferentially inhibiting cardiac sodium channel inactivation by binding to receptor site 3. Although JZTX-I also exhibits the interaction with channel isoforms expressing in mammalian and insect sensory neurons, its affinity for tetrodotoxin-resistant subtype in mammalian cardiac myocytes (IC50 = 31.6 nm) is approximately 30-fold higher than that for tetrodotoxin-sensitive subtypes in latter tissues. Not affecting outward delay-rectified potassium channels expressed in Xenopus laevis oocytes and tetrodotoxin-resistant sodium channels in mammal sensory neurons, JZTX-I hopefully represents a potent ligand to discriminate cardiac sodium channels from neuronal tetrodotoxin-resistant isoforms. Furthermore, different from any reported spider toxins, the toxin neither modifies the current-voltage relationships nor shifts the steady-state inactivation of sodium channels. Therefore, JZTX-I defines a new subclass of spider sodium channel toxins. JZTX-I is an alpha-like toxin first reported from spider venoms. The result provides an important witness for a convergent functional evolution between spider and other animal venoms.
ISSN: 0021-9258
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Physiology Section (-)
Toxicology and Pharmacology
× corresponding author
# (joint) last author

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