title: Molecular cloning and sequence analysis of cDNAs encoding a beta-toxin-like peptide and two MkTx I homologues from scorpion Buthus martensii Karsch.
abstract: Three full-length cDNAs, one encoding the precursor of a beta-toxin-like peptide (named BmKBT) and the other two encoding those of (MkTx I) homologues (named MkTx II and MkTx III, respectively), were isolated from a venom gland cDNA library of the Chinese scorpion Buthus martensii Karsch, by screening with a cDNA fragment generated by PCR. The encoded precursor of BmKBT contained 83 amino acid residues including a signal peptide of 19 residues, a mature peptide of 63 residues and an extra basic residue (Lys) which have to be removed in the processing step. The deduced amino acid sequence of BmKBT showed 52% homology to that of beta-neurotoxin TsVII isolated from scorpion Tityus serrulatus. However, the positions of disulfide bridges have a little variation between the two peptides. The precursors of MkTx II and MkTx III both contained 85 amino acid residues including a signal peptide of 19 residues, a mature peptide of 64 residues and two extra residues (Gly-Arg) which have to be removed in the processing step, too. There was high sequence similarity (90%) between the two peptides. The sequences of mature MkTx II and MkTx III were highly homologous with MkTx I isolated from scorpion Buthus martensii Karsch, both showing 90% identities.
authors.affiliation: Department of Biotechnology, College of Life Sciences, Institute of Virology, Wuhan University, Wuhan 430072, People's Republic of China.
authors.forename: X C
authors.initials: XC
authors.lastname: Zeng
authors.forename: W X
authors.initials: WX
authors.lastname: Li
authors.forename: S Y
authors.initials: SY
authors.lastname: Zhu
authors.forename: F
authors.initials: F
authors.lastname: Peng
authors.forename: Z H
authors.initials: ZH
authors.lastname: Zhu
authors.forename: H
authors.initials: H
authors.lastname: Liu
authors.forename: X
authors.initials: X
authors.lastname: Mao
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary; D015723:Gene Library; D008969:Molecular Sequence Data; D009498:Neurotoxins / Q000032:analysis*; D016133:Polymerase Chain Reaction; D012604:Scorpion Venoms / Q000032:analysis* / Q000302:isolation & purification; D012605:Scorpions; D017422:Sequence Analysis, DNA
chemical_list: D018076:DNA, Complementary; C418407:KBT toxin, Buthus martensii; D009498:Neurotoxins; D012604:Scorpion Venoms; C109067:TX1 toxin, Buthus; C109068:TX2 toxin, Buthus; C418406:TX3 toxin, Buthus martensii