title: Molecular cloning and characterization of Phoneutria nigriventer toxins active on calcium channels.
abstract: The aim of the present study was the molecular cloning of toxins active on calcium channels expressed by the spider Phoneutria nigriventer. Clones encoding the toxins Pn3-3A, Pn3-4A, Tx3-5, Pn3-5A, Tx3-6, Pn3-6A and Pn3-6B were identified from a cDNA library derived from the venom gland of this spider, revealing toxins of 49, 76, 45, 39, 55 and 58 amino acids residues, respectively, with polypeptide precursors being composed of three major portions: a signal peptide, a propeptide and finally, the mature toxin. A high degree of homology with the amino acid sequence was found between Pn3-3A and the neurotoxin Tx3-3 (identity of 79%), and between Pn3-4A and the neurotoxin Tx3-4 (identity of 95%). The deduced amino acid sequence for the mature polypeptides Tx3-5 and Tx3-6 confirms the polypeptide sequence previously published for these neurotoxins. In addition, the toxin Pn3-5A showed 58% identity to the Tx3-5 amino acid sequence, and the toxins Pn3-6A and Pn3-6B showed 85 and 33% identity, respectively, to the Tx3-6 amino acid sequence.
authors.affiliation: Departamento de Farmacologia, ICB, Universidade Federal de Minas Gerais, Av. Antonio Carlos 6627, Belo Horizonte, Minas Gerais 31 270 900, Brazil.
authors.forename: F C
authors.initials: FC
authors.lastname: Cardoso
authors.forename: L G
authors.initials: LG
authors.lastname: Pacífico
authors.forename: D C
authors.initials: DC
authors.lastname: Carvalho
authors.forename: J M N
authors.initials: JM
authors.lastname: Victória
authors.forename: A L G
authors.initials: AL
authors.lastname: Neves
authors.forename: C
authors.initials: C
authors.lastname: Chávez-Olórtegui
authors.forename: M V
authors.initials: MV
authors.lastname: Gomez
authors.forename: E
authors.initials: E
authors.lastname: Kalapothakis
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015220:Calcium Channels / Q000187:drug effects; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D015723:Gene Library; D008969:Molecular Sequence Data; D009498:Neurotoxins / Q000235:genetics* / Q000633:toxicity; D010455:Peptides / Q000235:genetics; D016415:Sequence Alignment; D017385:Sequence Homology; D013111:Spider Venoms / Q000235:genetics* / Q000633:toxicity; D013112:Spiders
chemical_list: D015220:Calcium Channels; D018076:DNA, Complementary; D009498:Neurotoxins; D010455:Peptides; D013111:Spider Venoms