3. Results
3.1. cDNA cloning of EqtIV
A positive clone of 858 bp was isolated from the A. equina cDNA library. Its
nucleotide and derived amino acid sequences are presented in Fig. 1. It contains a
63 bp 5'-untranslated region (UTR), 642 bp open reading frame (ORF) and 139
bp 3'-UTR. The ORF codes for the precursor of a new Eqt, which we named
EqtIV. The nucleotide sequence corresponding to the mature region is 94% and
93% identical to the sequences of EqtII and EqtV, respectively. Its deduced amino
acid sequence (179 residues), however, shows 88% and 86% identities to EqtII
and EqtV, respectively. The mature toxin region contains a putative cell
attachment Arg±Gly±Asp motif at positions 144±146. The mature region of EqtIV
is preceded by a 19 amino acid residue peptide, which appears to be a typical
Fi