FIGURE 3.

Design of a fusion expression vector to aid in solubilizing the expressed recombinant protein. Expression vectors containing a fusion protein or peptide tags may help increase the solubility of the target protein by promoting proper folding and stabilization. These fusions may be attached to either the N- or C-terminus. Various protein fusions and peptide tags are available for selection, however, they must be carefully chosen to be compatible with the target protein. Examples of protein fusion tags include glutathione-S-transferase (GST), mannose binding protein (MBP), while peptide tags include commonly utilized histidine (His). Plasmid display system technology makes use of fusion partners to attach the fusion and target protein to the plasmid to improve stability of the expressed protein. If selecting a fusion partner to use in a plasmid display system, consideration must be given to an appropriate and soluble fusion partner. For example, in the following figure the transcription factor Oct-1 is utilized which possesses a DBD that recognizes and attaches to the recognition sequence.