Abstract
A peptide with neurotoxic effect on mammals, purified from the venom of the spider Phoneutria nigriventer, was studied regarding its primary structure and its effects on voltage-gated calcium channels. The peptide, named ω-phonetoxin-IIA, has 76 amino acids residues, with 14 Cys forming 7 disulphide bonds, and a molecular weight of 8362.7 Da. The neurotoxicity is a consequence of the peptide’s blocking effects on high-voltage-activated (HVA) calcium channels. N-type HVA calcium channels of rat dorsal root ganglion neurons are blocked with affinity in the sub-nanomolar concentration range. The toxin also blocks L-type channels of rat β pancreatic cells, with an affinity 40 times lower. Although not studied in detail, evidence indicates that the toxin also blocks other types of HVA calcium channels, such as P and Q. No effect was observed on low-voltage-activated, T-type calcium channels. The significant homologies between ω-phonetoxin-IIA and the peptides of the ω-agatoxin-III family, and the overlapping inhibitory effects on calcium channels are discussed in terms of the structure-activity relationship.
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Received: 2 February 1998 / Received after revision and accepted: 23 March 1998
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Cassola, A., Jaffe, H., Fales, H. et al. ω-Phonetoxin-IIA: a calcium channel blocker from the spider Phoneutria nigriventer . Pflügers Arch 436, 545–552 (1998). https://doi.org/10.1007/s004240050670
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DOI: https://doi.org/10.1007/s004240050670