Grammotoxin

Grammotoxin is a toxin in the venom of the tarantula Grammostola spatulata.

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.

[1] Its chemical formula is: C177H268N52O50S6[2] Grammotoxin can be purified from Grammostola spatulata venom by reverse phase high performance liquid chromatography.

[4] As a result, the toxin preferentially binds to the closed channels.

Solution structure of omega-grammotoxin SIA. PDB entry 1koz [ 1 ]