Grammotoxin
Toxin
title: "Grammotoxin" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["neurotoxins", "ion-channel-toxins"] description: "Toxin" topic_path: "general/neurotoxins" source: "https://en.wikipedia.org/wiki/Grammotoxin" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Toxin ::
::figure[src="https://upload.wikimedia.org/wikipedia/commons/f/f1/1koz.jpg" caption="1koz}}{{Cite journal"] ::
| doi = 10.1016/S0022-2836(02)00595-8 | last1 = Takeuchi | first1 = K. | last2 = Park | first2 = E. | last3 = Lee | first3 = C. | last4 = Kim | first4 = J. | last5 = Takahashi | first5 = H. | last6 = Swartz | first6 = K. | last7 = Shimada | first7 = I. | title = Solution structure of omega-grammotoxin SIA, a gating modifier of P/Q and N-type Ca(2+) channel | journal = Journal of Molecular Biology | volume = 321 | issue = 3 | pages = 517–526 | year = 2002 | pmid = 12162963 Grammotoxin is a toxin in the venom of the tarantula Grammostola spatulata. It is a protein toxin that inhibits P-, Q- and N-type voltage-gated calcium channels (Ca 2+ channels) in neurons. Grammotoxin is also known as omega-grammotoxin SIA.
Chemistry
Grammotoxin is a 36 amino acid protein toxin, with the sequence Asp-Cys-Val-Arg-Phe-Trp-Gly-Lys-Cys-Ser-Gln-Thr-Ser-Asp-Cys-Cys-Pro-His-Leu-Ala-Cys-Lys-Ser-Lys-Trp-Pro-Arg-Asn-Ile-Cys-Val-Trp-Asp-Gly-Ser-Val (DCVRFWGKCSQTSDCCPHLACKSKWPRNICVWDGSV), and disulfide bridges between Cys2-Cys16, Cys9-Cys21 and Cys15-Cys30.
It forms an inhibitor cystine knot motif, common in spider toxins.
Its chemical formula is: C177H268N52O50S6
Grammotoxin can be purified from Grammostola spatulata venom by reverse phase high performance liquid chromatography.{{Cite journal | last1 = Lampe | first1 = R. A. | last2 = Defeo | first2 = P. A. | last3 = Davison | first3 = M. D. | last4 = Young | first4 = J. | last5 = Herman | first5 = J. L. | last6 = Spreen | first6 = R. C. | last7 = Horn | first7 = M. B. | last8 = Mangano | first8 = T. J. | last9 = Keith | first9 = R. A. | title = Isolation and pharmacological characterization of omega-grammotoxin SIA, a novel peptide inhibitor of neuronal voltage-sensitive calcium channel responses | journal = Molecular Pharmacology | volume = 44 | issue = 2 | pages = 451–460 | year = 1993 | doi = 10.1016/S0026-895X(25)13204-5 | pmid = 8394998
Mode of action
The toxin binding site on the channels has high affinity for the toxins when they are closed and low affinity when channels are activated.{{Cite journal | last1 = McDonough | first1 = S. I. | last2 = Lampe | first2 = R. A. | last3 = Keith | first3 = R. A. | last4 = Bean | first4 = B. P. | title = Voltage-dependent inhibition of N- and P-type calcium channels by the peptide toxin omega-grammotoxin-SIA | journal = Molecular Pharmacology | volume = 52 | issue = 6 | pages = 1095–1104 | year = 1997 | doi = 10.1124/mol.52.6.1095 | pmid = 9415720
References
References
- [http://www.sigmaaldrich.com/catalog/search/ProductDetail?ProdNo=G2795&Brand=SIGMA ω-Grammotoxin SIA from Grammostola spatulata venom, ≥98% (HPLC)]
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