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Background
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Jingzhaotoxin-III (ß-TRTX-Cj1alpha) has been isolated initially from the Chinese Tarantula spider Chilobrachys Jingzhao venom. Jingzhaotoxin-III selectively inhibits the voltage-dependent sodium channel Nav1.5 channel with an IC50 value close to 350 nM. It is inactive on Nav1.2, Nav1.4, Nav1.6 and Nav1.7 and should therefore be considered as an interesting research tool to discriminate between sodium channel subtypes. The toxin binds onto receptor site 4 presumably located on DIIS3-S4 linker of Nav1.5 and supposedly blocks Nav1.5 through a different mechanism than ProTx-II and Huwentoxin IV. ß-TRTX-Cj1alpha is composed of 36 amino acid residues including 6 cysteines cross-linked according to a C1-C4, C2-C5 and C3-C6 pattern.
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