title: Cloning and characterization of the pseudonajatoxin b precursor.
abstract: An Australian common brown snake, Pseudonaja textilis, is known to contain highly lethal neurotoxins. Among them, a long-chain alpha-neurotoxin, pseudonajatoxin b, has been identified. In this report, while presenting evidence for the presence of at least four such long-chain alpha-neurotoxins in the venom of P. textilis, we describe the characteristics of both the mRNA and the gene responsible for the synthesis of these neurotoxins. A precursor toxin synthesized from the gene has been identified as being capable of producing the isoforms possibly by post-translational modifications at its C-terminal end. Recombinant toxins corresponding to the precursor and its product have been found to possess similar binding affinities for muscular acetylcholine receptors (IC(50)=3x10(-8) M) and a lethality, LD(50), of 0.15 microg/g in mice.
authors.affiliation: Department of Biochemistry, Faculty of Medicine, National University of Singapore, 10 Medical Drive, Singapore 119260.
authors.forename: N
authors.initials: N
authors.lastname: Gong
authors.forename: A
authors.initials: A
authors.lastname: Armugam
authors.forename: P
authors.initials: P
authors.lastname: Mirtschin
authors.forename: K
authors.initials: K
authors.lastname: Jeyaseelan
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001315:Australia; D001483:Base Sequence; D003001:Cloning, Molecular; D004546:Elapid Venoms / Q000737:chemistry* / Q000235:genetics* / Q000633:toxicity; D017815:Elapidae / Q000235:genetics*; D005796:Genes; D008099:Liver / Q000378:metabolism; D008969:Molecular Sequence Data; D009498:Neurotoxins / Q000737:chemistry / Q000633:toxicity; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics* / Q000633:toxicity; D011994:Recombinant Proteins / Q000737:chemistry; D012045:Regulatory Sequences, Nucleic Acid; D015183:Restriction Mapping; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D004546:Elapid Venoms; D009498:Neurotoxins; D011498:Protein Precursors; D011994:Recombinant Proteins; C053022:pseudonajatoxin b