Purification Using Affinity Tag Technology

Affinity tag technology is a prerequisite for high and rapid purification of recombinant proteins in structural studies because of specific interactions of tags. Widely used tags are polyhistidine tags specific to metal-chelating ligands and glutathione S-transferase tag for glutathione-immobilized ligands. Furthermore, tags binding to antibodies, such as FLAG, Fc, and HA, are also popular for protein preparation and, in addition, are utilized for biological and biochemical analyses, e.g., western blotting, immunoprecipitation, immunofluorescence assay, and flow cytometry. Some tags improve the solubility of proteins. In this chapter, we introduce the features of these representative tags and show several practical examples.