Cloning and characterization of the cDNA sequences of two venom peptides from Chinese scorpion Buthus martensii Karsch (BmK)

From a cDNA library made from venom glands of Chinese scorpions of Buthus m artensii Karsch, full-length cDNAs encoding precursors of two venom peptide s have been isolated using a cDNA probe synthesized by polymerase chain rea ction. Sequence analysis of the cDNAs revealed that one encoded precursor w as 85 amino acid residues long including a signal peptide of 19 residues an d a mature peptide (named BmK T) of 66 residues, and another encoded precur sor was 84 residues long containing the same length signal peptide and a ma ture peptide (BmK M4 isoform. named BmK M4') of 64 residues. The analysis o f amino acid sequence similarity indicated that the BmK T was homologous wi th both mammalian and insect toxins from BmK scorpion or other scorpions. a nd the BmK M4' was highly homologous with the members of the mammalian neur otoxin family of BmK, having two point mutations in amino acid residue sequ ence compared to BmK M4, a natural toxin from BmK. (C) 2000 Elsevier Scienc e Ltd. All rights reserved.