Phrixotoxin-3  (PaurTx3 or Beta-theraphotoxin-Ps1a) is a valuable pharmacological tool to study voltage-gated sodium channels. Phrixotoxin-3, originally issued from the venom of the tarantula phrixotrichus auratus, has been shown to inhibit Na_v1.1, Na_v1.2, Na_v1.3, Na_v1.4 and Na_v1.5 with respective IC₅₀ values of 610 nM, 0.6 nM, 42 nM, 288 nM and 72 nM. It is thus considered as one of the most potent and almost selective modulator of Na_v1.2.

Description:

Product code: N/A.Category: Sodium channels.Tag: nav1.2.

AA sequence: Asp-Cys²-Leu-Gly-Phe-Leu-Trp-Lys-Cys⁹-Asn-Pro-Ser-Asn-Asp-Lys-Cys¹⁶-Cys¹⁷-Arg-Pro-Asn-Leu-Val-Cys²³-Ser-Arg-Lys-Asp-Lys-Trp-Cys³⁰-Lys-Tyr-Gln-Ile-OHDisulfide bridges: Cys²-Cys¹⁷, Cys⁹-Cys²³, and Cys¹⁶-Cys³⁰Length (aa): 34Formula: C₁₇₁H₂₄₅N₅₃O₄₇S₆Molecular Weight: 4059.9 DaAppearance: White lyophilized solidSolubility: water or saline bufferCAS number: Not availableSource: SyntheticPurity rate: > 97 %

Reference:

Four Novel Tarantula Toxins as Selective Modulators of Voltage-Gated Sodium Channel Subtypes

Four novel peptide toxins that act on voltage-gated sodium channels have been isolated from tarantula venoms: ceratotoxins 1, 2, and 3 (CcoTx1, CcoTx2, and CcoTx3) from Ceratogyrus cornuatus and phrixotoxin 3 (PaurTx3) from Phrixotrichus auratus. The pharmacological profiles of these new toxins were characterized by electrophysiological measurements on six cloned voltage-gated sodium channel subtypes expressed in Xenopus laevis oocytes (Na(v)1.1/beta(1), Na(v)1.2/beta(1), Na(v)1.3/beta(1), Na(v)1.4/beta(1), Na(v)1.5/beta(1), and Na(v)1.8/beta(1)). These novel toxins modulate voltage-gated sodium channels with properties similar to those of typical gating-modifier toxins, both by causing a depolarizing shift in gating kinetics and by blocking the inward component of the sodium current. PaurTx3 is one of the most potent peptide modulators of voltage-gated sodium channels described thus far from spider venom, modulating Na(v)1.2 with an IC(50) value of 0.6 +/- 0.1 nM. CcoTx1 and CcoTx2, differing by only one amino acid, are potent modulators of different voltage-gated sodium channel subtypes from the central nervous system, except for Na(v)1.3, which is only affected by CcoTx2. The potency of CcoTx3 is lower, although this toxin seems to be more selective for the tetrodotoxin-resistant channel subtype Na(v)1.5/beta(1) (IC(50) = 447 +/- 32 nM). In addition to these results, molecular modeling indicates that subtle differences in toxin surfaces may relate to their different pharmacological profiles. Furthermore, an evolutionary trace analysis of these toxins and other structurally related three-disulfide spider toxins provides clues for the exploration of toxin-channel interaction and future structure-function research. Bosmans, F. et al (2006) Four Novel Tarantula Toxins as Selective Modulators of Voltage-Gated Sodium Channel Subtypes. Molecular Pharmacology. PMID: 16267209

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