Merck, 401002-10UG, Iberiotoxin, Buthus tamulus, Recombinant, E. coli

General description
Recombinant Buthus tamulus iberiotoxin expressed in E. coli. A single polypeptide chain of 37 amino acids that displays about 68% sequence homology with charybdotoxin (ChTx). Acts as a selective, reversible blocker of high conductance, Ca²⁺-activated K⁺ channels (PK,Ca). rIbTx does not block other types of voltage-dependent ion channels, especially other types of K⁺ channels that are sensitive to inhibition by ChTx. Shown to block PK,Ca in excised membrane patches from bovine aortic smooth muscle, acting exclusively at the outer face of the channel (IC₅₀ = 250 pM). Causes a decrease in probability of channel opening and the channel open mean time. rIbTx appears to modulate ChTx binding by an allosteric mechanism.
Biochem/physiol Actions
Cell permeable: no
Primary Target
High conductance Ca2+-activated K+ channels
Product does not compete with ATP.
Reversible: yes
Target IC₅₀: 250 pM against high conductance Ca2+-activated K+ channels
potently inhibits Ca²⁺-activated K⁺ channels expressed in Xenopus oocytes
Preparation Note
Following reconstitution, aliquot and freeze (-20°C) for long-term storage or refrigerate (4°C) for short-term storage. Stock solutions are stable for up to 3 months at -20°C or up to 2 weeks at 4°C.
Reconstitute in Tris-buffered saline (100 mM NaCl, 10 mM Tris-HCl, pH 7.5) containing 0.1% BSA.
Other Notes
Pyr-Phe-Thr-Asp-Val-Asp-Cys⁷-Ser-Val-Ser-Lys-Glu-Cys¹³-Trp-Ser-Val-Cys¹⁷-Lys-Asp-Leu-Phe-Gly-Val-Asp-Arg-Gly-Lys-Cys²⁸-Met-Gly-Lys-Lys-Cys³³-Arg-Cys³⁵-Tyr-Gln-OH (disulfide bonds: 7 →28; 13 → 35; 17 → 33)
Vanelli, G., et al. 1994. J. Appl. Physiol.76, 1098.
Garcia, M.L., et al. 1991. J. Bioeng. Biomembr.23, 615.
Galvez, A., et al. 1990. J. Biol. Chem. 265, 11083.
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Disclaimer
Toxicity: Harmful (C)