Antibodies for fluorescent proteins and epitope tags

Fluorescent protein antibodies

Fluorescent proteins are indispensable tools in scientific research. By tagging proteins with bright, stable reporters, molecular processes can be visualised in real time. Our antibodies enhance these applications by enabling precise, reproducible detection of fluorescent tags, even when the fluorescence is weak or quenched.

Antibodies detecting Red Fluorescent Protein (RFP) and derivatives

Red fluorescent proteins (RFPs) were first isolated from Discosoma coral. Early RFPs, such as DsRed, tended to form tetramers, interfering with protein function. More recent RFP derivatives have been engineered into stable monomeric forms, collectively referred to as the mFruit family.

St John’s Laboratory offers a wide range of monomeric RFPs from the mFruit family, due to their range of diverse colours. These variants include mCherry, tdTomato , mScarlet, mRuby, and mOrange fluorescent protein, which are valued for their enhanced brightness, photostability, and reduced aggregation.

These RFP derivatives are widely used in cellular imaging and research as they offer several key advantages:

• Diverse spectral properties: RFP derivatives are available in a range of colours, from orange to deep red, allowing for multiplexed imaging experiments to visualise multiple proteins or cellular components simultaneously.
• Enhanced performance: These engineered variants have improved characteristics over earlier generations of fluorescent proteins, such as the tetrameric DsRed. Their monomeric structure minimises the risk of protein aggregation and interference with the function of the target protein.
• Superior photostability: RFP derivatives, such as mCherry and mScarlet, are highly photostable, meaning they resist irreversible photobleaching under prolonged or intense illumination. This is crucial for time-lapse imaging and advanced microscopy techniques.
• High brightness: RFP derivatives exhibit high brightness, a combination of their extinction coefficient and quantum yield, which results in a strong fluorescent signal even for low-abundance proteins.
• Enhances signal amplification when native fluorescence is weak.
• High specificity: no cross-reactivity with unrelated fluorophores.

Antibodies detecting key RFP derivatives

• DsRed antibody: Recognises the original DsRed protein and is still widely used in developmental biology and stem cell studies.

• mCherry Antibody / Anti-mCherry Antibody: mCherry antibodies detect mCherry, a monomeric red fluorescent protein commonly used in gene expression studies, fusion protein constructs and in vivo imaging. The antibody demonstrates excellent performance in Western blotting, confocal microscopy and flow cytometry applications.

• tdTomato antibody: tdTomato antibody detects tdTomato, a tandem dimer red fluorescent protein frequently used in transgenic animal models and reporter assays. This antibody allows precise detection of tdTomato fusion proteins in fixed tissues, cultured cells and protein extracts. It is an excellent tool for neuroscience imaging, cell tracking experiments and fluorescence microscopy.

• mRuby antibody: mRuby antibody recognises mRuby, a bright, monomeric form of RFP.

• mOrange Antibody: mOrange antibody detects mOrange, which is ideal for multiplex imaging when used alongside GFP, YFP or CFP.

Antibodies to Green Fluorescent Protein (GFP) and their derivatives

Green fluorescent protein (GFP) was originally isolated from the jellyfish Aequorea victoria. Early GFP constructs were prone to weak dimerisation, which in certain contexts interfered with protein function or localisation. Monomeric GFP variants contain a key mutation (A206K), which prevents this self-association, making these variants more reliable for use in fusion protein applications.

Advantages of anti-GFP and GFP derivative antibodies

• Signal amplification for enhanced detection: when native GFP fluorescence is weak.
• High specificity, with no cross-reactivity to unrelated fluorophores like RFP.
• Broad application in immunocytochemistry (ICC), immunofluorescence (IF), Western blotting, immunoprecipitation (IP) and FRET studies.
• Extensive range of formats available, including monoclonal and polyclonal formats for higher specificity and broader detection.

Antibodies detecting key GFP derivatives

• EGFP Antibody / Anti-EGFP Antibody: Recognises enhanced GFP (EGFP), which offers improved brightness compared to wild-type GFP. Anti-EGFP antibodies are extensively used in immunofluorescence, Western blotting, and live-cell imaging.
• EYFP Antibody / Anti-YFP Antibody: Detects EYFP, YFP, CFP, morange tag fusion proteins, with weak reactive against GFP tag. Anti-YFP antibodies enable sensitive detection of YFP fusion proteins in both fixed and live cells.
• ECFP Antibody / Anti-CFP Antibody: Anti-CFP antibody detects ECFP & CFP tag protein and are frequently employed in live-cell imaging, ICC and multicolour fluorescence studies.

Affinity tags and protein purification

Affinity tags are essential molecular tools used to simplify the detection, isolation, and functional study of recombinant proteins.

Applications at a glance:

• Small peptide tags (HA, Myc, FLAG, V5, His): Ideal for detection, localisation, immunoprecipitation (IP), and tandem tagging strategies.
• Larger fusion tags (GST, MBP, Strep): Advantageous for affinity purification, solubility, and stability enhancement.

St John’s Laboratory antibodies provide sensitive, specific detection to complement purification workflows.

1. Small peptide epitope tags

Compact (6–15 amino acids) and minimally disruptive, these tags are widely used for Western blotting, immunofluorescence, IP, and tandem tagging.

• HA tag antibody (anti-HA tag antibody): detects the HA epitope. This antibody is widely used for Western blotting, immunofluorescence, and immunoprecipitation of HA-tagged proteins. Its high sensitivity makes it an excellent choice for tracking recombinant protein expression and validating experimental constructs.
• Myc tag antibody (anti-Myc tag antibody): recognises the Myc epitope derived from the c-Myc protein. These antibodies are essential in gene expression studies, fusion protein detection, and protein localisation experiments. They work reliably across applications including flow cytometry, immunofluorescence and WB applications.
• FLAG tag antibody: is designed for the short DYKDDDDK peptide sequence, commonly used for protein tagging. It enables efficient detection in Western blotting, immunoprecipitation and chromatin immunoprecipitation (ChIP) experiments.
• V5 tag antibody: detects the V5 epitope. This antibody is used to track recombinant proteins in both mammalian and microbial systems for cell biology, virology and protein expression applications. It is particularly useful in co-immunoprecipitation assays and microscopy-based detection.
• His tag antibody (Anti histidine tag antibody / Anti his tag antibodies): This range of antibodies target polyhistidine tags (commonly 6x His) used in recombinant protein expression systems. They are essential tools for protein purification, Western blotting, and ELISA, providing sensitive detection of His-tagged proteins in bacterial, yeast, or mammalian expression systems.

2. Antibodies for larger fusion tags

We offer a range of antibodies for full-length proteins or structured domains that offer solutions for protein purification workflows, with enhanced solubility and increased stability for expressed proteins.

• GST tag antibody: provides sensitive detection of proteins fused to the glutathione S-transferase (GST) tag, a common tag used for purification and expression in E. coli. This antibody allows researchers to track GST-tagged proteins during purification workflows and validate their presence in SDS-PAGE, Western blotting, and functional assays.
• MBP tag antibody: is designed for proteins fused to Maltose Binding Protein (MBP), a large solubility-enhancing tag frequently used in bacterial expression systems. This antibody enables sensitive detection of MBP-tagged proteins in Western blotting, pull-down assays, and immunoprecipitation, while also serving as a validation tool alongside amylose-resin purification. Its dual role in solubility enhancement and purification monitoring makes it an important reagent for recombinant protein research.
• Strep tag antibody: detects proteins containing the Strep-tag sequence, often used in high-affinity purification systems. This antibody enables sensitive detection of Strep-tagged proteins in Western blotting, pull-down assays, and immunoprecipitation, making it an important tool for recombinant protein analysis.

Why Choose St John’s Laboratory Antibodies?

• Committed to providing high-quality antibody reagents and assays that advance research
• High specificity and sensitivity: minimising background, maximising reproducibility
• Validated across key applications: including WB, ELISA, IF, ICC, IP, ChIP, and flow cytometry
• Comprehensive catalogue: offering both fluorescent protein antibodies and epitope tag antibodies.

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