Fusion protein

A fusion protein is a recombinant protein with another protein added at the beginning or end. Fusion proteins are made by cloning the gene of interest and the attachment side by side on the vector before inserting it into the host. Fusion proteins are used to make purification easier, for example, the glutathione-S-transferase purification (GST) method attaches glutathione-S-transferase to the target protein which is then purified by its affinity for glutathione. A cleavage site can be inserted between the two to make it easier to separate them later if necessary.