, also known as an antigenic determinant, is a biological structure or sequence to which an antibody binds.
can be expressed with an epitope tag to enable easier identification, purification and detection. Epitope tagging eliminates the need to produce a new antibody for each different protein. The experimenter can choose the fitting tag epitope for the recombinant protein so that it can be manipulated in the desired experimental application such as
and affinity purification.