Hainantoxin IV

Hainantoxin-IV (HNTX-IV) is a peptide that was originally isolated from the venom of the Chinese bird spider Ornithoctonus hainana Liang (Selenocosmia hainana Liang). It has been reported that this peptide is a potent antagonist of tetrodotoxin-sensitive (TTX-S) voltage-gated sodium channels (VGSCs). It binds to TTX-S with an IC50value of 34 nM in adult rat dorsal root ganglion (DRG) neurons. Tetrodotoxin-resistant (TTX-R) voltage-gated sodium channels are not affected by hainantoxin IV. It probably interacts with the site 1 through a mechanism quite similar to that of TTX without affecting the activation and inactivation kinetics.