|PROSITE documentation PDOC60023 [for PROSITE entry PS60023]|
The spider venoms often contain many active peptides such as neurotoxins, lectins, inhibitors to enzyme, etc. These peptides are very important for spider's hunting and defending. During the long history of spider evolution, the peptides evolved into different structures and functions. Spider venoms possess a diverse array of peptide toxins composed of high number of cysteine residues varying from 6 to 14 . Several peptide toxins, collectively referred to as omega-toxins, block with differential selectivity the different types of voltage-gated Ca2+ channels.
Omega-agatoxins from Agelenopsis aperta are small disulfide rich polypeptides which are grouped in different classes according to their pharmacological properties against N, L and P/Q calcium currents. Some omega-agatoxins are very specific such as type I, II and IV omega-agatoxins, which respectively block L, N and P currents. Type III omega-agatoxins are less selective and block both N and L currents with the same potency. Type II and type III omega-agatoxins have clear similarity regarding the location of cysteine residues which have a C-x(6)-C-x(6,8)-C-x-C-C-x(5)-C arrangement [2,3].
The following spider toxins contain the same cysteine arrangement:
The pattern we have developed for this cysteine arrangement covers the last four cysteines.Note:
Type I and IV omega-agatoxins are unrelated to type II and III omega- agatoxins. They have different cysteine arrangements (respectively C-x(6)-C- x-C-x(6)-C-x-C-x(11)-C-x-C-x(7)-C-x(5)-C and C-x(7)-C-x(6)-C-C-x(4)-C-x(6)-C- x-C) [2,3].Expert(s) to contact by email:
September 2005 / First entry.
PROSITE method (with tools and information) covered by this documentation:
|1||Authors||Rajendra W. Armugam A. Jeyaseelan K.|
|Title||Toxins in anti-nociception and anti-inflammation.|
|2||Authors||Escoubas P. Diochot S. Corzo G.|
|Title||Structure and pharmacology of spider venom neurotoxins.|
|3||Authors||Rash L.D. Hodgson W.C.|
|Title||Pharmacology and biochemistry of spider venoms.|
|4||Authors||Cassola A.C. Jaffe H. Fales H.M. Castro Afeche S. Magnoli F. Cipolla-Neto J.|
|Title||omega-phonetoxin-IIA: a calcium channel blocker from the spider phoneutria nigriventer.|
|Source||Pflugers Arch. 436:545-552(1998).|