Figure 3.

Important motifs and conserved splicing elements of inteins. Inteins contain four important motifs: The N-terminal region with N₁ and N₂; and the C-terminal region with C₁ and C₂ motifs. The important splicing amino acid residues of each motif are indicated. The conserved amino acid residues (C, S, and T) on the C-extein are also indicated. These amino acids are also important for the splicing process to occur. A list of selected intein-associated proteins of bacteria, bacteriophages, viruses, and fungi, and their protein sequence alignment of conserved A, B, E, and F motifs, is also given.