Molecular Cloning and Analysis of BmKBT Genomic Sequence from Scorpion Buthus martensii Karsch

BmKBT is a toxic component purified from the venom of Chinese scorpion Buthus martensii Karsch (BmK), specially acting on Na + channel. Although it is structurally similar to β type Na + channel toxins, BmKBT is functionally similar to α type Na + channel toxins. Base on the known sequence of BmKBT isolated from the cDNA library of the venom gland, genomic BmKBT was cloned by PCR method. Sequence analysis of genomic BmKBT shows that BmKBT has an intron of 225 base pairs located at the end of the signal peptide encoding region. The intron of BmKBT is similar to the α type sodium ion channel toxins in the size, the location and the sequence consensus of the 5′splice donor, a putative branch point distance 47 base pairs upstream of the 3′splice receptor. Combining with the function of BmKBT, the genomic organization of BmKBT indicates that it is a membership between α and β type sodium ion channel toxin, which might serve as a useful matter to research evolution of the scorpion venom gene.