Spider Toxin Card | ArachnoServer

Toxin Name	ω-agatoxin-Aa3d (N-terminal fragment)
Source Species	*Agelenopsis aperta* (Western grass spider)
Toxin Group	Agatoxin
Description	ω-AGTX-Aa3d is a member of a family of insecticidal and vertebrate-active toxins from Agelenopsis aperta that block a wide range of voltage-gated calcium (Cav) channels. The toxin has not been fully sequenced; the primary structure shown below is an N-terminal fragment. The prototypic family member is ω-AGTX-Aa3a. The toxin blocks calcium channels in insect central neurons but not at peripheral neuromuscular junctions. In vertebrates, it is broadly activity against all high-threshold Cav1 channels and Cav2 channels, but it is ineffective at blocking Cav3 (T-type) channels. Its potency against Cav1 (L-type) and Cav2.2 (P/Q-type) channels is 370- and 15-fold less, respectively, than ω-AGTX-Aa3a. Curiously, the block of Cav2 channels by this family of toxins is only partial even at saturating concentrations of toxin. It has been suggested that the toxins occlude inward current by acting as a partial plug or "leaky lid" in the outer region of the channel vestibule. The binding sites for the prototypic family member ω-AGTX-Aa3a and ω-AGTX-Aa4a on Cav2.1 (P/Q-type) channels are distinct and non-overlapping. The toxin is present in A. aperta venom at low concentration (3 μM).
Discovered	1993