The FLAG™ tag (peptide sequence DYKDDDDK) is a short, hydrophilic protein tag commonly used in conjunction with antibodies in protein pull-downs to study protein–protein interactions. The FLAG tag may be inserted at the N terminus, the N terminus preceded by a methionine residue, the C terminus, or internal positions of the target protein. Because of its hydrophilic nature, the FLAG tag is commonly found on the surface of a fusion protein, which makes it more available as an epitope for binding to antibodies.

In addition, the high hydrophilicity and small size of the FLAG tag tend to interfere less with protein expression, proteolytic maturation, antigenicity, and function. FLAG tags are also easily removed by enterokinase (EK).

Quality Invitrogen antibodies specific to the FLAG tag are available for a variety of research needs. We also offer fluorescent and enzyme-conjugated versions for your added convenience. 

Featured product data

Immunofluorescence analysis of HeLa cells transfected with a construct containing a FLAG epitope tag. Cells were probed with a FLAG Epitope Tag monoclonal antibody conjugated to DyLight 550 dye ( Cat. No. MA1-91878-D550). Nuclei were stained with Hoechst™ 33342 dye (blue).


 

Western blot analysis of the FLAG epitope tag was performed by loading various amounts of E. coli lysate containing a multi-epitope tagged protein per well. The membrane was probed with a FLAG Epitope Tag monoclonal antibody conjugated to DyLight 680 dye (Cat. No. MA1-91878-D680).


Annotated product references

MA5-11251 was used in western blotting to investigate a rapid method for generating bi-specific antibodies. Carlring J, De Leenheer E, Heath AW (2011) A novel redox method for rapid production of functional bi-specific antibodies for use in early pilot studies. PLoS One 6: e22533.

MA5-11251 was used in flow cytometry and western blotting to perform high-throughput antibody screening using detergent-solubilized and biotinylated whole cell lysates as the antigen source. Cho YK, Shusta EV (2010) Antibody library screens using detergent-solubilized mammalian cell lysates as antigen sources. Protein Eng Des Sel 23: 567–577.

MA5-11251 was used in western blotting to develop a novel yeast display immunoprecipitation method for antigen isolation and characterization. Cho YK, Chen I, Wei X et al. (2009) A yeast display immunoprecipitation method for efficient isolation and characterization of antigens. J Immunol Methods 341: 117–126.


Related links

Tag, Dye, and Fusion Protein Antibodies

FLAG is a trademark of Sigma-Aldrich Co.