Protoxin I / ProTx-I, Blocker of voltage-gated sodium channels Protoxin I (ProTx-I; β-theraphotoxin-Tp1a) is a toxin that was originally isolated from the venom of Thrixopelma pruriens (Peruvian green velvet tarantula). This toxin reversibly inhibits the tetrodotoxin (TTX)-resistant channel Nav1.8 (IC50 = 27 nM) and Nav1.2, Nav1.5 and Nav1.7 with IC50 values between 50 and 100 nM. Furthermore, ProTx-I shifts the voltage dependence activity of T-type Cav3.1 channels (IC50= 50 nM) without affecting the voltage dependence of inactivation. ProTx-I is a valuable tool to discriminate between Cav3.1 and Cav3.2. ProTx-I technical information AA sequence: Glu-Cys2-Arg-Tyr-Trp-Leu-Gly-Gly-Cys9-Ser-Ala-Gly-Gln-Thr-Cys15-Cys16-Lys-His-Leu-Val-Cys21-Ser-Arg-Arg-His-Gly-Trp-Cys28-Val-Trp-Asp-Gly-Thr-Phe-Ser Disulfide bridges: Cys2-Cys16, Cys9-Cys21, Cys15-Cys28 Length (aa): 35 Formula: C171H245N53O47S6 Molecular Weight: 3987.50 Da Appearance: White lyophilized solid Solubility: water or saline buffer CAS number: Not available Source: Synthetic Purity rate: > 95 % http://www.smartox-biotech.com/en/sodium-channel/257-protx-i

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