Epitope tags are universal epitopes that are easily detected with commercially available antibodies. Epitope tags can be attached to a recombinant protein’s N- or C-terminal and don’t typically affect the function or structure. Commonly used epitopes are genetically engineered, such as V5, c-myc, HA, and FLAG. Using epitopes is an economical way to detect low abundance proteins that are low immunogenic that don’t currently have specific antibodies available.
Epitopes and their antibodies allow the detection of the recombinant protein in a wide variety of applications, including western blotting, immunoprecipitation, immunohistochemistry, immunofluorescence, and flow cytometry.
Choosing the right epitope for your protein requires some consideration. The size of the tag and solubility and how they may affect the overall charge should all be evaluated before making your decision. Only some epitopes are optimal for some applications; in some cases, adding multiple epitopes to a single protein can improve the options for downstream analysis. However, this is more likely to affect the protein’s structure, function, or localisation.