Figure 4. in vivo Applications of Protein Splicing.

A) Schematic representation of intein mediated peptide or protein cyclization. The target polypeptide is expressed flanked by Int^C and Int^N at the N- and C-termini, respectively. Protein trans-splicing (PTS) results in the formation of a new peptide bond between the N- and C-termini of the target and thus generates a circularized peptide or protein. B) Control of protein splicing through ligand-induced intein complementation. The splicing activity of artificially split inteins can be controlled by fusion to exogenous auxiliary domains (in the figure, a ligand binding domain). A triggering event (in the figure, ligand binding) causes a conformational change in the auxiliary domain, which induces intein reconstitution and subsequent protein splicing.