Figure 3

A major family expansion of Tribolium serpins and their phylogenetic relationships with the serpins from other insect species. The sequences of 29 Tribolium (Tc), 3 Drosophila (Dm), 3 Anopheles (Ag), 4 Apis (Am) and 5 Manduca (Ms) serpins are compared. Tribolium serpin2 (758 residues) and serpin26 (568 residues), much longer than a typical serpin (40-50 kDa), are excluded from the analysis. For simplicity, Tribolium serpins 1b, 15a, 20b and 28a are also eliminated because they are products of alternative splicing of the genes 1a, 15b, 20a and 28b, which differ only in the region coding for reactive site loop. As shown in the tree (left panel), extensive expansion gives rise to this group of highly similar genes (shaded blue) located in a small chromosomal region (right panel). Pink arrowheads at nodes denote bootstrap values greater than 800 for 1,000 trials. Putative 1:1, 1:1:1 or 1:1:1:1 orthologous relationship is indicated by green bars connecting the group members.