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Hainantoxin III

Hainantoxin III
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Size: 0.5 mg
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Hainantoxin III

Hainantoxin-III is a peptide that has been isolated from the venom of the Chinese bird spider Seleconosmia hainana. Hainantoxin-III specifically blocks mammalian neuronal tetrodotoxin-sensitive voltage-gated sodium channels (VGSCs). Hainantoxin III was found inactive on tetrodotoxin-resistant VGSCs and voltage-gated Ca2+ channels (both high and low voltage-activated). Hainantoxin-III strongly depressed the amplitude of rat DRG tetrodotoxin-sensitive Na+ currents with an IC50 value of 1.1 nM. Like Hainantoxin-IV, Hainantoxin-III causes a hyperpolarizing shift of about 10 mV in the voltage midpoint of steady-state Na+ channel inactivation. Similar to Huwentoxin-IV, Hainantoxin-III and -IV do not affect the activation and inactivation kinetics of Na+ currents. Hainantoxin-III inhibits Nav1.7 current amplitude without significantly altering the activation and inactivation kinetics. Hainantoxin-III increases the deactivation of the Nav1.7 current after extreme depolarizations. Hainantoxin-III seems to interact with site 4 and to trap the domain II voltage sensor in the closed state. The inhibition of Nav1.7 by hainantoxin-III is reversible upon washing, but no reversibility was observed for Hainantoxin-IV and Huwentoxin-IV. Hainantoxin-III was shown to block Nav1.1, Nav1.2, Nav1.3 and Nav1.7 expressed in HEK293 cells with IC50 values of 1.27 µM, 275 nM, 491 nM and 232 nM, respectively.

Product Type:
Peptides & proteins
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Molecular Weight:
3608.20 Da
Wang W., et al. (2003) Determination of disulfide bridges of two spider toxins: Hainantoxin-III and Hainantoxin -IV. J Venom Anim Toxins incl Trop Dis; Liu Z., et al. (2013) Structure and Function of Hainantoxin-III, a Selective Antagonist of Neuronal Tetrodotoxin-sensitive Voltage-gated Sodium Channels Isolated from the Chinese Bird Spider Ornithoctonus hainana. JBC