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	Toxin Name ω-agatoxin-Aa3b Source Species Agelenopsis  aperta (Western grass spider) Toxin Group Agatoxin Description ω-AGTX-Aa3b 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 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 Cav2.2 (P/Q-type) channels is similar to that of ω-AGTX-Aa3a but it is 130-fold less effective against Cav1 (L-type) channels. 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 (10 μM). Discovered 1993 This toxin last updated on Aug 20, 2010 Taxonomy Current Taxonomy Historic Taxonomy Kingdom Animalia Phylum Arthropoda Class Arachnida Order Araneae Infra-order Araneomorphae Family Agelenidae Genus Agelenopsis Species aperta Agelena aperta Agelenopsis aperta Agelenopsis aperta guttata Agelenopsis gertschi Biological Activity Neurotoxin Molecular Target ED50 IC50 Kd Pharmacophore Comment Calcium channel, voltage-gated (vertebrate): CaV2.2 2.4  nM Block of omega-conotoxin GVIA-sensitive Cav currents in chick brain synaptosomes Calcium channel, voltage-gated (invertebrate) 140 nM toxin yields a 25% block of Cav currents in locust thoracic ganglion neurons Calcium channel, voltage-gated (vertebrate): CaV1, non-specific 47.0  nM Block of L-type currents in guinea pig atrial myocytes Accessions Source Accession ArachnoServer AS000179 InterPro IPR005853 InterPro IPR013605 NCBI_Taxon 6908 Pfam PF08396 PIR B54252 PIR C54252 PIR D54252 PROSITE PS60023 UniProt P81744 Literature References Original Deposition References Ertel E.A., Warren V.A., Adams M.E., Griffin P.R., Cohen C.J., Smith M.M. Biochemistry 33:5098-5108 (1994) Type III omega-agatoxins: a family of probes for similar binding sites on L- and N-type calcium channels Other References Yan L., Adams M.E. J. Biol. Chem. 275:21309-21316 (2000) The spider toxin omega-Aga IIIA defines a high affinity site on neuronal high voltage-activated calcium channels McDonough S.I., Boland L.M., Mintz I.M., Bean B.P. J. Gen. Physiol. 119:313-28 (2002) Interactions among toxins that inhibit N-type and P-type calcium channels. Protein Information Disulfide Bonds Left Residue Right Residue Evidence 2 19 Predicted 9 25 Predicted 16 52 Predicted 18 40 Predicted 27 38 Predicted 59 67 Predicted Sequences Peptide Sequences >as:ω-agatoxin-Aa3b|sp:P81744 Toxin (Omega-Aga-IIIB) from the venom of the spider Agelenopsis aperta that blocks Cav1 and Cav2 channels SCIDFGGDCDGEKDDCQCCRSNGYCSCYNLFGYLKSGCKCEVGTSAEFRRICRRKAKQCY NSDPDKCVSVYKPKRR Full BLAST BLAST mature toxin only Toxin Synonyms Synonym Type ω-agatoxin-Aa3b Recommended full name ω-AGTX-Aa3b Recommended abbreviation ω-agatoxin IIIB Synonym ω-Aga-IIIB Synonym (abbreviation)
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