Overview
- Robinson, S.D. et al. (2023) Nat Commun., 14, 2977.
Soluble in DMSO. Prepare a concentrated stock solution by dissolving the lyophilized peptide in DMSO first (e.g., at a concentration between 100-1000x of the final working concentration). Once the peptide is completely dissolved in DMSO, slowly dilute the solution into the working buffer (or water) to the desired final working concentration.
Centrifuge all product preparations before use. It is recommended to keep the DMSO concentration as low as possible. For cell assays, a final concentration of 0.1%–0.5% DMSO (v/v) is considered safe. For other experiments, a 5% DMSO (v/v) concentration is recommended.
Alomone Labs Ectatotoxin-Rm4a modulates NaV1.7 channel currents in stably transfected HEK293 cells.A. Representative time course, showing the effect of 3 µM (green) Rm4a (#STR-010) on the normalized area of NaV1.7. NaV1.7 currents were elicited by a 10 ms voltage step from the holding potential of -90 mV to 0 mV, applied every 5 sec, using whole-cell voltage clamp technique.
B. Superimposed traces of NaV1.7 current after application of control (black) and of 3 μM Rm4a (green), taken from the recording in A.
- Robinson, S.D. et al. (2023) Nat Commun., 14, 2977.
- Robinson S. D. et al. (2024) J. Biol. Chem., 300, 105577.
Ectatotoxin-Rm4a (Rm4a), originally isolated from the venom of Rhytidoponera metallica (Australian green-headed ant), is a 26-amino acid cysteine-free peptide toxin that modulates voltage-gated sodium (NaV) channels, particularly NaV1.6 and NaV1.7 subtypes. Rm4a toxin induces sustained sodium currents by delaying inactivation and causing a hyperpolarizing shift in activation voltage. It exhibits higher potency for human Nav1.6 channels (EC50 = 196 ± 23 nM) compared to Nav1.7 (EC50 = 1.9 ± 0.4 µM) and Nav1.8 (EC50 = 8.4 ± 1.0 µM)1.
Rm4a toxin, along with other closely related ant venom peptides such as Delta-myrmicitoxin-Ta3a, Myrmicitoxin1-Pm1a, Myrmicitoxin1-Pm2a and Poneratoxin, represents a new class of NaV channel modulators. These toxins are structurally and functionally distinct from previously characterized peptide-based NaV modulators, offering valuable insights into the evolutionary adaptations of ant venom. The effects of these toxins on NaV channel currents more closely resemble those of “site 2” alkaloid toxins, such as batrachotoxin1,2.
The toxin's ability to prevent channel inactivation and shift the voltage-dependence of activation can lead to increased neuronal excitability and prolonged action potentials, ultimately resulting in enhanced pain signaling. In mice, Rm4a causes dose-dependent spontaneous nocifensive behaviors, further supporting its potential to induce pain1.
Ectatotoxin-Rm4a (#STR-010) is a highly pure, synthetic, and biologically active peptide toxin.
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