Genes and peptides from the scorpion Centruroides sculpturatus Ewing, thatrecognize Na+-channels

Sixteen different genes were cloned from the venomous glands of Centruroide s sculpturatus Ewing using RNA extracted from scorpions collected in Tucson , Arizona. Based on the amino acid sequence similarities of the proteins co ded by these Genes, all together there are 22 different structural componen ts in this venom, thought to be specific for Na+-channels. The genes report ed contain signal peptides with 19 amino acid residues followed by mature p eptides of 63-66 amino acid residues in length. One of them correspond to t oxin I (CsEI), a known scorpion toxin specific for Na+-channels. Four diffe rent Genes are almost identical to variant 1 (Csv1), presenting only one am ino acid change from the original protein. For variant 2 (Csv2) four relate d genes were found, with only one amino acid change in their primary sequen ces. Another gene resembles to variant 3 (Csv3, the best known Centruroides sculpturatus toxin), with only three amino acid changes in their primary s equences. Additionally, two genes show variations only on the nucleotide se quence at level of the signal peptides, and several genes clearly show sequ ences that suggest post-transcriptional modifications, during the maturatio n process. A phylogenetic tree was Generated with the primary structures av ailable and three main divergent branches were found. (C) 2001 Elsevier Sci ence Ltd. All rights reserved.