mCherry-Tag Polyclonal Antibody

What is mCherry and why is it commonly used as a fusion protein tag in research?

mCherry is a monomeric red fluorescent protein (mRFP) belonging to the mFruits family, derived from Discosoma sp. It consists of 236 amino acid residues with a molecular weight of approximately 26.7 kDa . mCherry is widely preferred in research due to its:

• Superior photostability compared to first-generation RFPs

• Monomeric nature that minimizes aggregation in fusion proteins

• Brightness and pH resistance

• Rapid maturation time

• Distinct spectral properties that facilitate multiplexing experiments

mCherry can function as a hetero-FRET (Fluorescence Resonance Energy Transfer) acceptor and probe for homoFRET experiments due to its high peak molar absorptivity and folding efficiency . As a reporter protein, it enables tracking of gene expression, protein localization, and trafficking in various experimental systems.

How do I select the appropriate host species for my mCherry-Tag polyclonal antibody?

The selection of host species should be based on:

Consider your experimental system when selecting the host species. For example, chicken anti-mCherry antibodies (e.g., ab205402) are particularly useful for mouse or rabbit tissue work due to reduced background signal . For multi-labeling experiments with rabbit primary antibodies against other targets, choose goat (AB0040-200) or mouse anti-mCherry antibodies .

What are the optimal dilution ranges for mCherry-Tag polyclonal antibodies across different applications?

Optimal dilution ranges vary by application and specific antibody:

Always perform a preliminary titration with each new lot of antibody. For example, some researchers report no difference in signal when using the mCherry primary antibody at dilutions between 1:1,000 and 1:5,000 for immunohistochemistry .

Why might I observe weak or absent endogenous mCherry fluorescence despite confirmed expression?

Multiple factors can contribute to weak endogenous mCherry fluorescence:

• Fusion protein interference: When mCherry is fused to another protein, particularly G-protein coupled receptors (GPCRs), its fluorescence capacity may be limited .

• Fixation sensitivity: Aldehyde-based fixatives can partially quench mCherry fluorescence. Research shows that antibody amplification dramatically improves visualization of mCherry fusion proteins in fixed tissue .

• Tissue thickness and opacity: Light scattering and absorption in thick tissues can reduce detectable fluorescence.

• Expression levels: Low expression levels may result in fluorescence below detection threshold.

• Viral construct variables: The detectability of mCherry fusion proteins can vary between viral constructs, requiring optimization for each new construct .

Recommended solution: Implement immunohistochemical amplification. Studies show this approach consistently provides a stronger signal when mCherry fusion protein is used as a reporter protein. For example, in tissue from AAV5-GFAP-hM4D-mCherry injected animals, endogenous mCherry fluorescence was barely detectable even at high magnification, while immunohistochemical amplification resulted in dramatically improved labeling .

How can I address the issue of mCherry's short isoform interfering with fusion protein studies?

Research has identified that mCherry contains a shorter functional isoform that can interfere with its use as a reporter or fusion tag . This issue originates from:

• An alternative translation initiation site (ATIS) at methionine residue 10 (M10)

• An SD-like sequence preceding this methionine

• Translation of this short isoform produces functional, fluorescent protein independent of your fusion construct

This can significantly affect the interpretation of protein localization and expression studies . Solutions include:

• Mutation strategy: Substitute M10 with glutamine or leucine to maintain structural properties while preventing short isoform production. These substitutions preserve the stabilizing interactions with tyrosine residue Y43 through H-bond formation (glutamine) or Van der Waals interactions (leucine) .

• Use mCherry V1: Consider using the short isoform (V1) directly as your reporter, as it resembles mRFP1.1 and eliminates the problem of dual isoform expression .

• SD sequence deoptimization: Modify the SD-like sequence preceding M10 to reduce recognition by ribosomes .

Laboratory testing shows these modified versions maintain fusion protein functionality while eliminating the short isoform production that can confound experimental interpretation .

How can I quantitatively measure secreted proteins using mCherry fusion constructs?

Microplate reader-based fluorescence detection of mCherry fusion proteins offers several advantages over traditional Western blot or ELISA methods for secreted protein quantification:

• Superior dynamic range: 4.5 orders of magnitude versus 2.5 orders for Western blot

• Enhanced linearity: R² value of >0.99 compared to 0.91 for Western blot

• Comparable sensitivity: Detection threshold of 1-2 fmol of fusion protein

• Direct measurement: No additional reagents (antibodies, substrates) required

• Higher throughput: Multiple samples processed simultaneously

Methodology:

• Generate an mCherry fusion with your secreted protein of interest (e.g., MMP-9-mCherry)

• Transfect cells (e.g., HEK293) with the fusion construct

• Collect culture media at desired timepoints (detectable as early as 6 hours post-transfection)

• Directly measure fluorescence using a microplate reader with appropriate excitation/emission settings

• Calculate concentration using a standard curve of purified mCherry

This approach allows for both extracellular (secreted) and intracellular retention quantification, providing insight into secretion efficiency under different experimental conditions .

What controls should I include when using mCherry-Tag polyclonal antibodies for immunodetection?

Rigorous controls are essential for accurate interpretation of results:

For fusion proteins, include controls expressing unfused mCherry to distinguish between fusion protein-specific issues and antibody performance. When performing co-localization studies, single-color controls are essential to assess bleed-through .

What methodological approaches can optimize detection of mCherry fusion proteins in fixed tissue samples?

Optimizing detection requires addressing multiple variables:

• Fixation protocol optimization:

  • Brief fixation (4% PFA for 1-2 hours) often preserves more fluorescence than extended fixation

  • Post-fixation washing in PBS with 0.1% Triton X-100 improves antibody penetration

• Antibody amplification procedure:

  • Day 1: Wash sections in TBS (3×5 min), block in TBS-Plus with 3% normal serum and 0.3% Triton-X (30 min), incubate in anti-mCherry primary antibody (1:1000-1:5000) in 0.3% Triton-X/TBS for 24h at 4°C

  • Day 2: Wash in TBS (3×5 min), incubate in fluorophore-conjugated secondary antibody (1:1000) for 2h at room temperature, wash again in TBS (3×5 min)

• Signal enhancement strategies:

  • TSA (Tyramide Signal Amplification) can provide 10-100× signal enhancement

  • Anti-mCherry primary followed by biotinylated secondary and streptavidin-conjugated fluorophore increases sensitivity

  • HRP-conjugated secondaries with fluorescent substrates offer another amplification option

• Imaging optimization:

  • Use spectral imaging to separate autofluorescence from specific signal

  • Consider longer exposure times with lower excitation intensity to reduce photobleaching

  • Z-stack acquisition with deconvolution can improve signal-to-noise ratio

Research demonstrates that immunohistochemical amplification can transform barely detectable mCherry signal into robust labeling, particularly for fusion proteins with GPCRs or in tissues with high background autofluorescence .

How do different mCherry-Tag polyclonal antibodies compare in their reactivity with other red fluorescent protein variants?

Different commercial antibodies show varying cross-reactivity patterns with red fluorescent protein variants:

When selecting an antibody for experiments involving multiple fluorescent proteins, consider both desired and unwanted cross-reactivity. For example, if you need to distinguish between mCherry and GFP-tagged proteins in the same sample, AB0040-200 is specifically noted not to recognize GFP .

What methodological considerations are important when using mCherry-Tag polyclonal antibodies for protein quantification?

When using mCherry-Tag polyclonal antibodies for protein quantification:

• Standard curve generation:

  • Use purified recombinant mCherry protein at known concentrations

  • Prepare standard curve with at least 5-7 points spanning the expected concentration range

  • Include blank controls (no mCherry)

• Linear range determination:

  • Western blot densitometry: Typically 0.05-10 ng with R² value of ~0.91

  • Fluorescence detection: Wider dynamic range (4.5 orders of magnitude) with R² value >0.99

  • ELISA: Determine specific range for your antibody via titration

• Normalization strategies:

  • For Western blot, normalize to loading controls (e.g., GAPDH, β-actin)

  • For fluorescence, normalize to cell number or total protein content

  • Consider dual-tag approach (e.g., mCherry plus FLAG) for validation

• Technical replication:

  • Perform triplicate measurements to account for technical variation

  • Include inter-assay calibrators for experiments performed on different days

For highly accurate quantification, direct fluorescence measurement of mCherry fusion proteins offers superior linearity and dynamic range compared to antibody-based detection methods. In one study, the calculated MMP-9-mCherry concentration in cell culture media was 0.49 ng/μL based on fluorescent detection, comparable to the Western blot result .

How can I optimize multi-color immunofluorescence experiments using mCherry-Tag polyclonal antibodies?

Successful multi-color immunofluorescence with mCherry-Tag antibodies requires careful planning:

• Antibody host species selection:

  • Choose complementary host species to avoid cross-reactivity

  • Example: Rabbit anti-mCherry paired with mouse antibodies against other targets

• Fluorophore selection and spectral separation:

  • When using direct mCherry fluorescence plus antibody detection:

    • Avoid red-spectrum secondary antibodies that overlap with mCherry (λem ≈ 610 nm)

    • Optimal choices: Alexa Fluor 488/FITC (green), Alexa Fluor 647/Cy5 (far-red)

  • When using antibody detection of mCherry:

    • Choose non-overlapping fluorophores (e.g., Alexa Fluor 488 for mCherry detection)

• Imaging considerations:

  • Perform single-color controls to set acquisition parameters

  • Use sequential scanning to minimize bleed-through

  • Consider spectral unmixing for closely overlapping fluorophores

Example of successful multiplexing: Immunofluorescent analysis of HEK293 cells transfected with pFin-EF1-mCherry vector using rabbit anti-mCherry at 1/1000 dilution (green secondary). The endogenous red mCherry fluorescence and green antibody staining co-localized in transfected cells, resulting in an orange signal in merged images, while DAPI (blue) stained all nuclei .

What methodological approaches can address the challenge of detecting low-abundance mCherry fusion proteins?

Detecting low-abundance mCherry fusion proteins requires enhanced sensitivity techniques:

• Signal amplification systems:

  • Tyramide Signal Amplification (TSA): Can increase sensitivity 10-100 fold

    • Protocol: Primary antibody → HRP-conjugated secondary → Tyramide-fluorophore reagent

  • Biotin-streptavidin amplification:

    • Protocol: Primary antibody → Biotinylated secondary → Streptavidin-fluorophore (multiple fluorophores per streptavidin)

• Concentration techniques for secreted proteins:

  • TCA precipitation of culture media

  • Centrifugal filter concentration (e.g., Amicon Ultra)

  • Immunoaffinity purification with anti-mCherry antibodies

• Optimized Western blot detection:

  • Extended primary antibody incubation (overnight at 4°C)

  • High-sensitivity chemiluminescent substrates (e.g., SuperSignal West Femto)

  • Extended exposure times with cooled CCD camera

• Alternative direct fluorescence detection:

  • Microplate reader-based fluorescence detection can detect as little as 1-2 fmol of fusion protein

  • Flow cytometry for cellular samples with compensation for autofluorescence