期刊
PEPTIDES
卷 30, 期 6, 页码 1042-1048出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.peptides.2009.02.018
关键词
Toxin; Expression; Tetrodotoxin-sensitive sodium channel; Whole-cell recording
资金
- Scientific Research Fund of Hunan Provincial Education Department [07A035]
- Key Project of Chinese Ministry of Education [208096]
- Huo Ying Dong Education Foundation [111023]
- Program for New Century Excellent Talents in University [NCET-07-0279]
Jingzhaotoxin-34 (JZTX-34) is a 35-residue polypeptide from the venom of Chinese tarantula Chilobrachys jingzhao. Our previous work reported its full-length cDNA sequence encoding a precursor with 87 residues. In this study we report the protein expression and biological function characterization. The toxin was efficiently expressed by the secretary pathway in yeast. Under whole-cell patch-clamp mode, the expressed JZTX-34 was able to inhibit tetrodotoxin-sensitive (TTX-S) sodium currents (IC50 similar to 85 nM) while having no significant effects on tetrodotoxin-resistant (TTX-R) sodium currents on rat dorsal root ganglion neurons. The inhibition of TTX-S sodium channels was completely reversed by strong depolarization (+120 mV). Toxin treatment altered neither channel activation and inactivation kinetics nor recovery rate from inactivation. However, it is interesting to note that in contrast to huwentoxin-IV, a recently identified receptor site-4 toxin from Ornithoctonus huwena venom, 100 nM JZTX-34 caused a negative shift of steady-state inactivation curve of TTX-S sodium channels by approximately 10 mV. The results indicated that JZTX-34 might inhibit mammalian sensory neuronal sodium channels through a mechanism similar to HWTX-IV by trapping the 1154 voltage sensor in the resting conformation, but their binding sites should not overlay completely. (C) 2009 Elsevier Inc. All rights reserved.
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