Multiple tandem epitope tagging for enhanced detection of protein expressed in mammalian cells.

Epitope tagging is a valuable tool for quick detection, isolation, and analysis of protein-protein interaction, without prior knowledge of the target protein. The FLAG epitope tag, one of the most widely used tags, is an eight amino acid peptide that can be detected by anti-FLAG monoclonal antibody. In the present study, we have examined the detection sensitivity of a protein fused to three tandem FLAG epitopes by Western blot analysis, immunoprecipitation, and immunohistochemical analysis using anti-FLAG M2 antibody. We find that the triple FLAG epitope significantly enhances the sensitivity of detection of fusion protein expressed in mammalian cells.