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.
The V5 tag is a 14 amino acid peptide derived from a small epitope (Pk) on the P and V proteins of simian virus 5 (SV5), a member of the paramyxovirus family. The V5 tag can be used to detect expression of recombinant proteins in bacteria, yeast, insects, and mammalian cell systems.