title: Sequence of the cDNA coding for the lethal neurotoxin Tx1 from the Brazilian "armed" spider Phoneutria nigriventer predicts the synthesis and processing of a preprotoxin.
abstract: A cDNA library was constructed from the venom glands of the Brazilian "armed" spider, Phoneutria nigriventer, and a clone coding for Tx1, a lethal toxin, was identified and sequenced. The sequence data derived from this cDNA clone combined with the previously determined amino acid sequence predict that Tx1 is initially synthesized as a preprotoxin. Four segments (comprising the signal sequence, a short, 15-amino acid, glutamate-rich sequence, the functional toxin, and 2 glycine residues) can be distinguished. The structure of the preprotoxin and the proposed processing steps required to form the mature Tx1 toxin show similarities with the synthesis and processing of omega-agatoxin IA.
authors.affiliation: Centro de Pesquisa e Desenvolvimento, Fundação Ezequiel Dias, Belo Horizonte (MG), Brazil.
authors.forename: M R
authors.initials: MR
authors.lastname: Diniz
authors.forename: M J
authors.initials: MJ
authors.lastname: Paine
authors.forename: C R
authors.initials: CR
authors.lastname: Diniz
authors.forename: R D
authors.initials: RD
authors.lastname: Theakston
authors.forename: J M
authors.initials: JM
authors.lastname: Crampton
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D011498:Protein Precursors / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013111:Spider Venoms / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D013112:Spiders
chemical_list: D009479:Neuropeptides; D011498:Protein Precursors; D013111:Spider Venoms; C064022:Tx1 neurotoxin; D004247:DNA