Epitope tagging is a recombinant DNA method by which a protein encoded by a cloned gene is made immunoreactive to a known antibody. Major areas ofapplication include monitoring protein expression, localizing proteins at thecellular and subcellular levels, and protein purification, as well as the analysis of protein topology, dynamics and interactions. Due to their small size, theyare unlikely to affect the tagged protein's biochemical properties.S1 tag is an epitope tag composed of a nine-r