Reliable, reproducible data depends on the quality of the antibodies you are using.

Epitope tag antibodies are highly specific monoclonal and polyclonal antibodies with the most common dye and enzyme conjugates used by researchers.

Epitope tags are small strings of peptides that are incorporated into the protein of interest during synthesis. They enable study of recombinant proteins in instances where protein-specific antibodies are not available or not appropriate for your experimental design.

By virtue of small size, epitope tag antibodies are less likely to interfere with protein function. Antibodies against these tags are well characterized and highly-specific, allowing you to track expressed proteins within cells, for affinity purification, and for the detection of proteins in immunoassays, such as western blotting, ELISA and immunofluorescence.

Epitope tags are also frequently used with recombinant protein cell cultures to allow researchers to selectively extract a target protein from the endogenous samples.

ThermoFisher offer a wide selection of primary antibodies specific to epitope and affinity tags, fluorescent dyes, and fusion proteins. For popular targets, conjugates to biotin, HRP, DyLight™ dyes and Alexa Fluor™ dyes are available.

Below are some of the most popular tags and how to use them.

FLAG Tag antibodies

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).

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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).

Find out more about FLAG Tag antibodies on the ThermoFisher website.

His Tag antibodies

The his-tag is a series of six to nine histidine residues generally fused to either the carboxy or amino terminus of a recombinant protein. The small size of the his-tag, compared with other common epitope tags, makes it less likely to obstruct the target protein’s structure or function and more suitable to use under denaturing conditions.

The string of histidine residues binds to several types of immobilized metal ions, including nickel, cobalt and copper. The binding to metal ions under specific buffer conditions, allows for the simple purification and detection of his-tagged proteins. 

His-Tag antibodies provide another dependable method for the detection and purification of tagged target proteins without a protein-specific antibody or probe.

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Immunofluorescence analysis of Histidine tag (6x-His) was done on HEK-293 cells. Left: Untransfected control; Right: anti-His (in red) on His-tagged fusion proteins in HEK293 cells. The cells were labeled with 6x-His Epitope Tag Monoclonal Antibody (Cat. No. MA1-21315). Both counterstained with DAPI (in blue.)

Invitrogen™ his-tag antibodies reliably detect recombinant his-tagged proteins. Each antibody is validated for use in applications such as ELISA, western blot, flow cytometry, immunofluorescence, immunohistochemistry, immunocytochemistry, and immunoprecipitation.

HA Tag antibodies

The HA (hemagglutinin) tag is derived from the human influenza virus HA protein. It has been extensively used as a general antibody epitope tag and is well-characterized.

HA tag antibodies provide a dependable method for the detection and purification of tagged target proteins without a protein-specific antibody or probe.

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Immunofluorescent analysis of HeLa cells transfected with a construct containing an HA epitope tag. Formalin fixed cells were permeabilized with 0.1% Triton™ X-100 in TBS for 10 minutes at room temperature and blocked with 1% Thermo Scientific™ Blocker™ BSA (Cat. No. 37525) for 15 minutes at room temperature. Cells were probed with a DyLight™ 488-conjugated HA epitope tag monoclonal antibody (Cat. No. 26183-D488) at a dilution of 1:25 for at least 1 hour at room temperature. Nuclei (blue) were stained with Hoechst 33342 dye (Cat. No. 62249). Images were taken on a Thermo Scientific™ ArrayScan™ imager at 20x magnification.

Invitrogen™ HA tag antibodies reliably detect recombinant HA tagged proteins, and each antibody is validated for use in a variety of applications.

Myc Tag antibodies

The Myc tag, derived from the c-Myc protein, is a popular epitope tag for detecting the expression of recombinant proteins in yeast, bacteria, insect, and mammalian cell systems. The Myc tag may be fused to either the N-terminus or C-terminus of a protein.

The well-characterized Myc tag provides a reliable method for the detection and purification of tagged target proteins without a protein-specific antibody or probe.

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Immunofluorescent analysis of c-Myc (green) in HEL 11.4 induced IPS cells grown for a few days on Matrigel-coated chamber slides. Cells fixed in 4% paraformaldehyde were permeabilized with 0.1% Triton X-100 for 15 minutes at room temperature. Cells were probed with a c-Myc monoclonal antibody (Cat. No. MA1-980) at a dilution of 1:200 overnight at 4°C, washed with PBST, and incubated with a fluorescein-conjugated secondary antibody at a dilution of 1:100 for 1 hour at room temperature. Nuclei (blue) were stained with DAPI and cells were analyzed by fluorescence microscopy at 20X magnification.

Invitrogen™ Myc tag antibodies are designed to dependably detect recombinant Myc-tagged proteins, and each antibody is validated for use in many applications.

V5 Tag antibodies

The V5 tag is derived from a small epitope (Pk) found on the P and V proteins of the paramyxovirus of simian virus 5 (SV5). The V5 tag is generally used with all 14 amino acids (GKPIPNPLLGLDST), but it may also be used with a shorter 9-amino acid (IPNPLLGLD) sequence.

V5 tag antibodies provide a dependable method for the detection and purification of tagged target proteins without a protein-specific antibody or probe.

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Immunofluorescence analysis of V5 tag was done on HEK-293 cells transiently overexpressing V5-His -LacZ. The cells were fixed with 4% paraformaldehyde for 15 minutes, permeabilized with 0.25% Triton™ X-100 for 10 minutes, and blocked with 5% BSA for 1 hour at room temperature. The cells were labeled with V5 Tag Mouse Monoclonal Antibody (Cat. No. 377500) at a dilution of 1:500 in 1% BSA and incubated for 3 hours at room temperature and then labeled with Alexa Flour® 488 Rabbit Anti-Mouse IgG Secondary Antibody (Cat. No. A11059) at a dilution of 1:400 for 30 minutes at room temperature (Panel a: green). Nuclei (Panel b: blue) were stained with SlowFade® Gold Antifade Mountant with DAPI (S36938). F-actin (Panel c: red) was stained with Alexa Fluor® 594 Phalloidin (Cat. No. A12381). Panel d is a merged image showing cytoplasmic localization. Panel e is untransfected HEK-293 cells.

Invitrogen™ V5 tag antibodies are designed to reliably detect recombinant V5-tagged proteins, and each antibody is validated for use in many applications.

GST Tag antibodies

The GST (glutathione S-transferase) tag is derived from a protein encoded by the parasite Schistosoma japonicum. The 26 kDa GST tag is typically fused to the N-terminus of a recombinant protein.

When expressed, GST quickly folds into a stable and highly soluble protein, resulting in greater expression and solubility of recombinant proteins with the GST tag. This can be especially helpful when expressing proteins in bacteria.

The GST protein also has a strong affinity for its substrate, GSH (glutathione), and GST-tagged fusion proteins can be detected or purified based on the binding of GST to GSH.

However, the GST tag is relatively large compared with other common epitope tags, and it may interfere with some protein functions. In these cases, it may be easily removed by protease cleavage. 

GST tag antibodies provide another dependable method for the detection and purification of tagged target proteins without a protein-specific antibody or probe. 

Invitrogen™ GST tag antibodies reliably detect recombinant GST-tagged proteins, and each antibody is validated for use in a variety of applications. Convenient purification kits and resins are also offered for GST-tagged protein purification and manipulation.

Find out more