What is the role of the protein tag? Does the fusion tag need to be removed during the experiment?

The fusion tag of recombinant protein refers to a specific protein, polypeptide, or oligopeptide tag that is fused and expressed at the N-terminal or C-terminal of the target protein using DNA in vitro recombination technology. The recombinant protein binds with the specific ligand coated on the solid matrix through the fusion tag, which makes the recombinant protein fixed and purified, greatly simplifying the detection of the recombinant protein, while retaining most of the structure of the natural protein, and achieving the functions of increasing solubility, preventing degradation, promoting secretion, and facilitating purification. Commonly used tags include His, GST, SUMO, Flag, Fc, etc. If the fusion tag is small and the immunogenicity is weak, it generally does not need to be removed, which will not affect the subsequent application and research of proteins, such as His tag and Fc tag. However, some large labels need to be removed, such as Dsb protein, FkpA protein, GST protein, SUMO label, etc.