title: Cloning, cDNA sequence analysis and patch clamp studies of a toxin from the venom of the armed spider (Phoneutria nigriventer).
abstract: The cDNAs (Tx3-2 and Pn3A) encoding precursor of toxin Tx3-2 and an isoform called Pn3A have been isolated from a library constructed from stimulated venom glands of the spider Phoneutria nigriventer. The cDNA of Tx3-2 reveals the presence of a signal peptide of 21 amino acids and of an intervening propeptide (with 16 amino acids) preceding the toxin sequence, which was followed by additional amino acid residues at the C-terminus (C-terminal peptide), implying post-translational modifications of the synthesised peptide. The deduced amino acid sequence for the mature toxin confirms the previous sequence published. In addition, by using the whole-cell patch clamp technique, we have determined that purified Tx3-2 decreases L-type currents present in GH3 cells. Finally, the presence of the cDNA Pn3A, with high sequence identity with Tx3-2, reveals the existence of a putative new toxin showing, at the cDNA level, 85.4% identity in its whole segment.
authors.affiliation: Departamento de Farmacologia, Instituto de Ciências Biològicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
authors.forename: E
authors.initials: E
authors.lastname: Kalapothakis
authors.forename: C L
authors.initials: CL
authors.lastname: Penaforte
authors.forename: R M
authors.initials: RM
authors.lastname: Leão
authors.forename: J S
authors.initials: JS
authors.lastname: Cruz
authors.forename: V F
authors.initials: VF
authors.lastname: Prado
authors.forename: M N
authors.initials: MN
authors.lastname: Cordeiro
authors.forename: C R
authors.initials: CR
authors.lastname: Diniz
authors.forename: M A
authors.initials: MA
authors.lastname: Romano-Silva
authors.forename: M A
authors.initials: MA
authors.lastname: Prado
authors.forename: M V
authors.initials: MV
authors.lastname: Gomez
authors.forename: P S
authors.initials: PS
authors.lastname: Beirão
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015220:Calcium Channels / Q000187:drug effects*; D019976:Cloning, Organism; D018076:DNA, Complementary / Q000737:chemistry; D015723:Gene Library; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000235:genetics*; D021382:Protein Sorting Signals; D013111:Spider Venoms / Q000145:classification / Q000235:genetics* / Q000633:toxicity
chemical_list: D015220:Calcium Channels; D018076:DNA, Complementary; D010455:Peptides; D021382:Protein Sorting Signals; D013111:Spider Venoms