A cDNA sequence encoding a neurotoxin-homolog fromBungarus multicinctus

The venoms of both Elapidae and Hydrophiidae are mixtures of proteins some of which are blockers of the rucotinic acetylcholine receptor (1). They are classified into shortneurotoxins (60 to 62 residues), long-neurotoxins (70 to 74 residues) and x-neurotoxins (66 residues) (2). Some peptides are classified as neurotoxin-homologs with unknown pharmacological activity (1). Here we present the first nucleotide sequence of a cDNA encoding the precursor of such a neurotoxin-homolog from snake venom. This cDNA was isolated from a library prepared from poly(A) RNA extracted from the venom glands of one specimen of Bungarus multicinctus. The longest open reading frame encodes a signal peptide (underlined) of 21 residues followed by a polypeptide chain of 66 residues. The signal peptide amino acid sequence is homologous to those described for shortneurotoxins (3, 4) and x-neurotoxins (5). Sequence alignment of the polypeptide with the amino acid sequences of neurotoxins homologs n° and 106 (1) revealed a conserved pattern of the amino acids. The 5' terminal non coding sequence is highly homologous to that of short-neurotoxins (3, 4) and, with an extra 27 bases insert (doubly underlined), to that of x-neurotoxins (5). ACKNOWLEDGEMENTS