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ProTx-II, Nav1.7 selective blocker

ProTx-II (ProTx-2, Protoxin II) is a toxin that was originally isolated from Thrixopelma pruriens (Peruvian green velvet tarantula). ProTx-II inhibits both tetrodotoxin-sensitive and  tetrodotoxin-resistant voltage-gated sodium channels. ProTx-II inhibits activation by shifting the voltage-dependence of channel activation to more positive potentials. ProTx-II blocks Nav1.7  with an IC50 value of around 300 pM, Nav1.2 Nav1.5 and Nav1.6 with IC50 values of 41 nM, 79 nM and 26 nM respectively. It also acts on Cav3.1/CACNA1G and interacts more weakly with the related T-Type channel Cav3.2/CACNA1H but potently inhibits the L-type calcium channel Cav1.2/CACNA1C. ProTx-II blocks action potential propagation in nociceptors.

ProTx-II Nav1.7 blocker - Bioassay resultsProTx-II #07PTX002 efficiently blocks the human Nav1.7 channel. Families of transiently-expressed human Nav1.7 current traces in control and in the presence of 1 nM ProTx-II showing more than 50% current inhibition. Currents were evoked by depolarizing pulses from a holding potential of -80 mV to step potential varying from -60 to 30 mV. The IC50 value for current inhibition by ProTx-II is 0.31 nM.

Full bioassay results

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AA sequence: Tyr-Cys2-Gln-Lys-Trp-Met-Trp-Thr-Cys9-Asp-Ser-Glu-Arg-Lys-Cys15-Cys16-Glu-Gly-Met-Val-Cys21-Arg-Leu-Trp-Cys25-Lys-Lys-Lys-Leu-Trp-OH
Disulfide bonds: Cys2-Cys16, Cys9-Cys21, Cys15-Cys25
Length (aa): 30
Formula: C168H250N46O41S8
Molecular Weight: 3826.65 Da
Appearance: White lyophilized solid
Solubility: water or saline buffer
CAS number: 484598-36-9
Source: Synthetic
Purity rate: > 95 %

Structural Basis of Nav1.7 Inhibition by a Gating-Modifier Spider Toxin.
The Role of Disulfide Bond Replacements in Analogues of the Tarantula Toxin ProTx-II

Spider-venom peptides that target voltage-gated sodium channels: pharmacological tools and potential therapeutic leads

Evidence for multiple effects of ProTxII on activation gating in Na(V)1.5

ProTx-II, a selective inhibitor of Nav1.7 sodium channels, blocks action potential propagation in nociceptors

ProTx-I and ProTx-II: gating modifiers of voltage-gated sodium channels

Differential phospholipid binding by site 3 and site 4 toxins. Implications for structural variability between voltage-sensitive sodium channel domains

Two tarantula peptides inhibit activation of multiple sodium channels

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