Fig. 4

Eukaryotic inteins insert at conserved, structurally flexible regions of host proteins. Intein-containing proteins with PDB structures (Prp8 – 5GMK, VMA1 – 3J9T, ThrRS – 3UGQ, and GLT – 1EA0) were selected to build ConSurf maps, which indicate the degree of conservation after structural alignment. Mauve indicates highly conserved, whereas cyan is more variable as shown in the key. The first residue of the C-extein, shown as spheres, is highlighted in yellow and indicates intein insertion site. Prp8i-a, VMA1i-a, and GLTi-a are in structurally flexible, yet highly conserved sites. The ThrRS intein is inserted in a structured α-helix. Linear cartoons were also generated using Pro-Origami and are shown above the ConSurf maps. Residue numbering indicates the region of protein used in the Pro-Origami model. The black arrow shows intein insertion site and the number corresponds to the highlighted residue in the ConSurf structure. Structure representations are as follows: α-helix – gray rectangle, β-strand – gray arrow, flexible boundary - black line