cDNA Sequences of Two Anti-mammals Neurotoxins from Scorpion Buthus martensii Karsch

The total mRNA was prepared and purified from the venom gland of scorpion Buthus martensii Karsch (BmK). The cDNA library of this venom gland was then constructed using reverse transcription. Two cDNAs encoding the anti-mammalian neurotoxins, named as BmK M1 and BmK M9, were selectively amplified by PCR and sequenced. Both have open reading frames of 252 bp encoding 84 residues of the toxin precursors, including a 19 amino acid signal peptide, the mature toxin with 64 residues, and an additional Arg tail at the carboxyl-terminus which was removed during post-protein processing. The deduced amino acid sequence of BmK M1 was completely identical with the known sequence of the natural toxin BmK M4, whereas the other BmK M9 shared a high homology with the natural toxin BmK M4, differing only in two residues. The cDNA of BmK M1 showed 87.2% homology with that of the African scorpion Lqh alphaIT.