The E Tag is a 13-peptide epitope commonly fused to the N- or C- termini of recombinantly expressed proteins. The E Tag (amino acid sequence: GAPVPYPDPLEPR) is a popular epitope tag that can be engineered to a protein through recombinant DNA technology. The E tag contains 13 amino acids and has a molecular weight of 1.4 kDa. Antibodies to the E-tag may be a useful tool in the detection and investigation of E-tagged proteins. Anti-E Tag antibodies facilitate the detection, isolation, and purification of E-tagged target proteins without a protein-specific antibody or probe. Epitope tags are useful for the labeling and detection of proteins using immunoblotting, immunoprecipitation, and immunostaining techniques. Because of their small size, they are unlikely to affect the tagged protein’s biochemical properties.