V5 Epitope Tag Peptide: Atomic Facts for Precision Protein Tagging

Executive Summary: The V5 Epitope Tag Peptide (GKPIPNPLLGLDST) is a synthetic 14-amino-acid sequence derived from the P and V proteins of simian virus 5, widely used for protein tagging in molecular biology (APExBIO). It is recognized by high-affinity anti-V5 antibodies, enabling robust detection and purification in Western blotting and immunoprecipitation workflows (Miyoshi et al., 2021). The peptide demonstrates excellent solubility (≥71.08 mg/mL in DMSO, ≥107.2 mg/mL in ethanol, ≥55.4 mg/mL in water) for flexible experimental conditions. Empirical studies show minimal interference with protein function, supporting its use in recombinant virus construction and advanced imaging. The V5 tag is validated for multiplexed, high-specificity assays and is intended for research use only (internal dossier).

Biological Rationale

The V5 Epitope Tag Peptide was engineered to address the need for a small, minimally invasive tag enabling reliable detection, differentiation, and purification of recombinant proteins. Its 14-residue sequence (GKPIPNPLLGLDST) is absent from most eukaryotic proteomes, reducing background and cross-reactivity (APExBIO). The tag can be genetically fused to the N- or C-terminus of proteins, facilitating identification of exogenous constructs in complex lysates. High-affinity monoclonal antibodies against the V5 tag support sensitive immunodetection, as demonstrated in Western blotting, immunoprecipitation, and advanced microscopy (Miyoshi et al., 2021). The V5 tag’s unique sequence and immunological profile make it particularly suitable for multiplexed detection alongside other epitope tags such as FLAG or HA, supporting modern proteomic and imaging workflows (see contrast: This article details atomic solubility and stability data not covered in linked review).

Mechanism of Action of V5 Epitope Tag Peptide

The V5 Epitope Tag Peptide functions by serving as a unique antigenic determinant fused to a target protein. When expressed in cells or organisms, the tag is recognized by anti-V5 monoclonal antibodies with high specificity and affinity. This recognition occurs under native or denaturing conditions, enabling detection in Western blot, immunoprecipitation, ELISA, and immunostaining. The tag's small size (14 amino acids; 1.4 kDa) minimizes structural or functional disruption of the target protein (APExBIO). Anti-V5 antibodies, including fast-dissociating variants, bind transiently or stably, supporting both endpoint and dynamic single-molecule imaging applications (Miyoshi et al., 2021). The peptide can be delivered as a synthetic standard or encoded in DNA for genetic fusion. Its solubility in DMSO (≥71.08 mg/mL), ethanol (≥107.2 mg/mL), and water (≥55.4 mg/mL) allows for convenient stock preparation and experimental flexibility. The tag is stable when stored desiccated at –20°C (see contrast: This article provides updated benchmarking and solubility metrics).

Evidence & Benchmarks

• The V5 tag (GKPIPNPLLGLDST) supports robust detection and purification of recombinant proteins when fused to either terminus, enabling high-sensitivity Western blotting and immunoprecipitation (Miyoshi et al., 2021).
• Anti-V5 monoclonal antibodies exhibit high specificity, with minimal cross-reactivity in human, mouse, and rat lysates, supporting multiplexed detection workflows (Miyoshi et al., 2021).
• The tag demonstrates minimal interference with protein folding or function, as validated in recombinant virus construction and expression studies (APExBIO).
• V5-tagged proteins are efficiently captured and eluted via immunoprecipitation using immobilized anti-V5 antibodies under native and denaturing conditions (internal atomic fact review).
• Fast-dissociating anti-V5 antibodies (Fab probes) enable super-resolution single-molecule imaging, revealing dynamic protein turnover in live-cell and tissue contexts (Miyoshi et al., 2021).
• Peptide solubility enables preparation of concentrated stocks (≥107.2 mg/mL in ethanol), supporting high-throughput screening and assay scalability (APExBIO).

Applications, Limits & Misconceptions

The V5 Epitope Tag Peptide is validated for a spectrum of molecular biology applications, including:

• Western blotting for detection of low-abundance recombinant proteins.
• Immunoprecipitation and co-immunoprecipitation to map protein–protein interactions.
• Affinity purification for downstream mass spectrometry or functional assays.
• Multiplexed imaging in advanced microscopy (e.g., diSPIM, super-resolution) (Miyoshi et al., 2021).

The tag is not suitable for diagnostic or therapeutic use in humans or animals (APExBIO). Overexpression or improper fusion may occasionally disrupt protein localization or stability; optimization is recommended for each target (see contrast: This article expands on troubleshooting and optimization strategies).

Common Pitfalls or Misconceptions

• The V5 tag is not universally compatible with all protein folds; steric hindrance or misfolding can occur if fused within structured domains.
• Endogenous proteins rarely contain the V5 sequence, but confirm absence via proteome analysis to avoid false positives.
• Anti-V5 antibodies vary in affinity/dissociation kinetics; select validated clones for single-molecule or live-cell applications (Miyoshi et al., 2021).
• Peptide standards should be dissolved in recommended solvents (e.g., DMSO, ethanol, water) to ensure full solubility and reproducibility.
• The product is not intended for diagnostic or therapeutic purposes.

Workflow Integration & Parameters

Fusion and Expression: The V5 tag can be genetically inserted at the N- or C-terminus, or internally, provided it does not disrupt protein structure. DNA sequence encoding the tag (v5 tag dna sequence) should be codon-optimized for the host organism (APExBIO).

Detection: Typical workflows include lysis of expressing cells/tissues, SDS-PAGE, protein transfer, and probing with anti-V5 antibodies. For immunoprecipitation, anti-V5 agarose or magnetic beads are used. Advanced imaging applications utilize fluorescently labeled Fab fragments with rapid binding kinetics, as established in diSPIM and IRIS super-resolution platforms (Miyoshi et al., 2021).

Storage & Handling: The synthetic peptide is supplied as a solid; store desiccated at –20°C. Prepare stocks in DMSO, ethanol, or water at concentrations up to the solubility limit. Avoid repeated freeze–thaw cycles (APExBIO).

For expanded troubleshooting and benchmarking, see this workflow guide (contrast: The present article details atomic solubility and dissociation metrics not covered in linked troubleshooting summary).

Conclusion & Outlook

The V5 Epitope Tag Peptide, available from APExBIO as product A6005, delivers sequence-specific, high-affinity detection and purification with minimal functional interference. Its robust solubility, compatibility with advanced imaging, and validated benchmarks in multiplexed assays make it a gold standard for research protein tagging. Ongoing advances in antibody engineering and imaging modalities will further expand the utility of the V5 tag in quantitative proteomics and live-cell workflows. For detailed specifications and ordering, consult the V5 Epitope Tag Peptide product page.