This is a family of potent toxins that function as ion-channel inhibitors for several different ions. Omega-Grammotoxin SIA is a VSCC antagonist that inhibits neuronal N- and P-type VSCC responses [1]. Huwentoxin-IV, from the Chinese bird spider, is a highly potent neurotoxin that specifically inhibits the neuronal tetrodotoxin-sensitive voltage-gated sodium channel in rat dorsal root ganglion neurons [2]. Hainantoxin-4, from the venom of spider Selenocosmia hainana, adopts an inhibitor cystine knot structural motif like huwentoin-IV, and is a potent antagonist that acts at site 1 on tetrodotoxin-sensitive (TTX-S) sodium channels [3]. Study of the molecular nature of toxin-receptor interactions has helped elucidate the functioning of many ion-channels [4].

1: Isolation and pharmacological characterization of omega-grammotoxin SIA, a novel peptide inhibitor of neuronal voltage-sensitive calcium channel responses. Lampe RA, Defeo PA, Davison MD, Young J, Herman JL, Spreen RC, Horn MB, Mangano TJ, Keith RA; Mol Pharmacol. 1993;44:451-460. PMID:8394998

2: Function and solution structure of huwentoxin-IV, a potent neuronal tetrodotoxin (TTX)-sensitive sodium channel antagonist from Chinese bird spider Selenocosmia huwena. Peng K, Shu Q, Liu Z, Liang S; J Biol Chem. 2002;277:47564-47571. PMID:12228241

3: Isolation and characterization of hainantoxin-IV, a novel antagonist of tetrodotoxin-sensitive sodium channels from the Chinese bird spider Selenocosmia hainana. Liu Z, Dai J, Chen Z, Hu W, Xiao Y, Liang S; Cell Mol Life Sci. 2003;60:972-978. PMID:12827284

4: Use of venom peptides to probe ion channel structure and function. Dutertre S, Lewis RJ; J Biol Chem. 2010;285:13315-13320. PMID:20189991