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8.B.3.1.3 Huwentoxin-4 precursor of 89 aas. This lethal neurotoxin acts selectively on tetrodotoxin-sensitive (TTX-S) voltage-gated sodium channels. A heterobivalent ligand (mu-conotoxin KIIIA (TC# 8.B.28.1.4), which occludes the pore of the NaV channels, and an analogue of huwentoxin-IV, a spider-venom peptide that allosterically modulates channel gating) slows ligand dissociation and enhances potency (Peschel et al. 2020).
Accession Number:	P83303
Protein Name:	Huwentoxin-4
Length:	89
Molecular Weight:	9997.00
Species:	Ornithoctonus huwena (Chinese bird spider) (Selenocosmia huwena) [29017]
Number of TMSs:	1
Location¹ / Topology² / Orientation³:	Secreted¹
Substrate

Structure:
Pfam:	PF07740
Gene Ontology GO:0005576 C:extracellular region GO:0042734 C:presynaptic membrane GO:0019870 F:potassium channel inhibitor activity GO:0019871 F:sodium channel inhibitor activity GO:0009405 P:pathogenesis GO:0007268 P:synaptic transmission
References (4) [1] “cDNA sequence analysis of seven peptide toxins from the spider Selenocosmia huwena.” Diao J.et.al. 14757201 [2] “Molecular diversification based on analysis of expressed sequence tags from the venom glands of the Chinese bird spider Ornithoctonus huwena.” Jiang L.et.al. 18482741 [3] “Function and solution structure of huwentoxin-IV, a potent neuronal tetrodotoxin (TTX)-sensitive sodium channel antagonist from Chinese bird spider Selenocosmia huwena.” Peng K.et.al. 12228241 [4] “Tarantula huwentoxin-IV inhibits neuronal sodium channels by binding to receptor site 4 and trapping the domain II voltage sensor in the closed configuration.” Xiao Y.et.al. 18628201
1MB6 2M4X 2M4Z 2M50 5T3M 5TLR 6W6O

Predict TMSs (Predict number of transmembrane segments)

1:	MVNMKASMFL ALAGLVLLFV VCYASESEEK EFSNELLSSV LAVDDNSKGE ERECLEIFKA 
61:	CNPSNDQCCK SSKLVCSRKT RWCKYQIGK