Alignment of three-finger toxins from snake venoms. Protein sequences were obtained from the NCBI database and are presented with their accession numbers. The signal peptide is similar in all the proteins and is shown in grey color; for those protein sequences whose signal peptide is not available, it is kept blank. The number of sequences of closely related homologues is shown in brackets. Based on structural identity, the mature protein is divided into several segments (S1–S9). To emphasize sequence similarities, segments with >50% identity are given similar colors, whereas <50% are given dissimilar colors. The gaps are inserted to optimize the alignments and shown as '-', and some of the functionally important amino acid residues are underlined (see text for details). The intron-exon boundary is marked with vertical red dashed lines.