Toxin Name ω-agatoxin-Aa1a
Source Species Agelenopsis  aperta (Western grass spider)
Toxin Group Agatoxin
Description Insecticidal toxin that inhibits neuromuscular transmission in both vertebrates and insects by blocking voltage-gated calcium (Cav) channels on presynaptic terminals. Reduces quantum content at fly neuromuscular junctions and blocks calcium action potentials in insect central neurons. The exact Cav subtypes targeted by ω-AGTX-Aa1a remain to be determined; however, it is likely to be primarily a Cav1 subtype(s) based on its ability to block dihydropyridine-sensitive L-type barium currents in rat dorsal root ganglion (DRG) neurons and its inability to inhibit the binding of the Cav2 blocker ω-conotoxin GVIA to chick synaptosomal membranes. Present in venom at a concentration of 0.1 mM.

ω-AGTX-Aa1a has an unusual heterodimeric structure. The toxin precursor is post-translationally cleaved to yield a major fragment of 66 residues that is covalently linked via disulfide bond to a smaller fragment of 3 residues. The summary figure below shows only the primary structure of the major subunit; this fragment is linked to a Ser-Pro-Cys tripeptide that corresponds to the C-terminus of the precursor molecule. The overall disulfide framework for this molecule has not yet been determined.
Discovered 1988
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This toxin last updated on Aug 20, 2010

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