THE CDNA AND GENOMIC DNA-SEQUENCES OF A MAMMALIAN NEUROTOXIN FROM THESCORPION BUTHUS-MARTENSII KARSCH

The cDNA library of venomous glands of the scorpion Buthus martensii K arsch (BmK) was constructed. A cDNA encoding a mammalian neurotoxin co rresponding to the known alpha-type toxin, BmK M1, was amplified by po lymerase chain reaction (PCR) and cloned, and its full-length sequence was determined. The open reading frame encoded the precursor of BmK M 1 with 84 amino acid residues, including a signal peptide of 19 residu es, a mature toxin of 64 residues and an additional C-terminal residue Arg which might be cleaved off by proteinase postprocessing immediate ly after protein synthesis. Based on the determined cDNA sequence and using the total DNA of the scorpion as a template, the gene of BmK MI was also amplified by PCR and sequenced. The genomic DNA sequence reve aled an intron of 408 base pairs present within the signal peptide reg ion. Both the intron and exon of BmK M1 share about 75% similarity wit h those of AaH I', another alpha-type mammalian neurotoxin in the scor pion Androctonus australis Hector. (C) 1997 Elsevier Science Ltd.