Certificate of Analysis

ProTx-I

Name: ProTx-I
Brand: Alomone Labs
SKU: STP-400

β-theraphotoxin-Tp1a, Beta-theraphotoxin-Tp1a, Protoxin-I, ProTx-1, Protoxin-1, ProTx I

A Blocker of Na_V, Ca_V3.1, K_V2.1 and TRPA1 Channels

Cat #: STP-400

Alternative Name β-theraphotoxin-Tp1a, Beta-theraphotoxin-Tp1a, Protoxin-I, ProTx-1, Protoxin-1, ProTx I

Lyophilized Powder yes

Bioassay Tested

Origin Synthetic peptide

MW: 3988 Da

Purity: >98% (HPLC)

Effective concentration 10-100 nM.

Sequence ECRYWLGGCSAGQTCCKHLVCSRRHGWCVWDGTFS.

Modifications Disulfide bonds between Cys²-Cys¹⁶, Cys⁹-Cys²¹, Cys¹⁵-Cys²⁸.

Structure

Molecular formula C₁₇₁H₂₄₅N₅₃O₄₇S₆.

CAS No.: 484598-35-8

Activity ProTx-I inhibits voltage-gated Ca²⁺ (Ca_V3.1), K⁺ (K_V2.1), and all Na⁺ channels tested (Na_V1.2, Na_V1.5, Na_V1.7 and Na_V1.8). The toxin shifts the voltage-dependence of channel activation to more positive potentials.

Accession number P83480.

Shipping and storage Shipped at room temperature. Product as supplied can be stored intact at room temperature for several weeks. For longer periods, it should be stored at -20°C.

Solubility Any aqueous buffer. Centrifuge all product preparations before use (10000 x g 5 min).

Storage of solutions Up to two weeks at 4°C or three months at -20°C.

Our bioassay

Alomone Labs ProTx-I inhibits Na_V1.5 currents in stably transfected HEK293 cells.
A. Time course of ProTx-I (#STP-400) action. Current amplitudes were plotted as a function of time. Holding potential was -100 mV and currents were stimulated every 10 seconds by a voltage ramp of 50 msec from holding potential to +60 mV. 50 nM ProTx-I was perfused in the period marked by the horizontal bar (green). B. Superimposed traces of Na_V1.5 currents before and during 3 min application of 50 nM ProTx-I.

Scientific background

Native ProTx-I has been isolated from the venom of the tarantula Thrixopelma pruriens. It was purified on the basis of its ability to reversibly inhibit the tetrodotoxin (TTX)-resistant Na channel Na_V1.8. ProTx-I was also found to be an inhibitor of Na_V1.5, Na_V1.7 and Na_V1.3 with IC₅₀ values below 100 nM. Furthermore, ProTx-I shifts the voltage dependence activity of Ca_V3.1 (α1G) (IC₅₀ ~50 nM) without affecting the voltage dependence of inactivation^1,2. ProTx-I also blocks TRPA1 channel with an IC₅₀ of 0.39 µM³.

Structurally, ProTx-I is shown to belong to the inhibitory cystine knot (ICK) family of peptidyl toxins interacting with voltage-gated ion channels.

Target Na_V, Ca_V3.1, K_V2.1, TRPA1 channels

Peptide Content: 100%

Lyophilized Powder

Image & Title ProTx-I

Alomone Labs ProTx-I and ProTx-II inhibit T-type Ca_V channels.ProTx-I (#STP-400) was applied to mouse thalamic neurons and ProTx-II (#STP-100) was tested on mouse DRGs. ProTx-I blocks native mouse Ca_V3.1 channel and recombinant human Ca_V3.1 channel currents similarly, and blocks to a lesser extent Ca_V3.2 and Ca_V3.3 channel currents. ProTx-II blocks Ca_V3.2 channels more potently than the other T-type currents.Adapted from Bladen, C. et al. (2014) Mol. Brain 7, 36. with permission of BioMed Central.

Last update: 06/11/2022

For research purposes only, not for human use

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