V5 Epitope Tag Peptide (GKPIPNPLLGLDST): Atomic Benchmarks for Protein Detection and Purification

Executive Summary: The V5 Epitope Tag Peptide is a synthetic 14-amino-acid tag (GKPIPNPLLGLDST) derived from simian virus 5, used in molecular biology for high-fidelity protein labeling and purification (APExBIO). The peptide exhibits ≥107.2 mg/mL solubility in ethanol, ≥71.08 mg/mL in DMSO, and ≥55.4 mg/mL in water at room temperature, enabling flexible experimental conditions. High-affinity anti-V5 antibodies recognizing this tag have been validated in Western blotting, immunoprecipitation, and single-molecule microscopy (Miyoshi et al., 2021). Minimal functional interference with fusion proteins or viral constructs has been demonstrated. The peptide is supplied as a solid, stable at -20°C under desiccation, and intended exclusively for research use.

Biological Rationale

The V5 Epitope Tag Peptide (GKPIPNPLLGLDST) originates from the P and V proteins of simian virus 5 (SV5), a member of the Paramyxoviridae family [product page]. Its sequence is not found in most eukaryotic or prokaryotic proteomes, reducing background in host cell lysates [related article]. The tag is genetically fused to the N- or C-terminus of recombinant proteins, enabling their differentiation from endogenous proteins. High-specificity anti-V5 monoclonal antibodies have been developed, facilitating reliable immunodetection and single-molecule imaging (Miyoshi et al., 2021). Compared to larger tags, the 14-residue V5 tag exhibits minimal steric hindrance and low immunogenicity, supporting its widespread adoption in molecular cloning, protein tracking, and advanced microscopy workflows.

Mechanism of Action of V5 Epitope Tag Peptide

The V5 tag functions as an epitope recognized by dedicated monoclonal antibodies. When fused to a protein of interest, the tag creates a distinct epitope unambiguously targeted by anti-V5 antibodies. This specificity enables the use of immunodetection methods such as Western blot, immunoprecipitation (IP), and immunofluorescence. The high-affinity interaction ensures strong signal-to-noise ratios for detection. Fast-dissociating anti-V5 antibodies, as demonstrated by Miyoshi et al., can be exploited for dynamic single-molecule imaging and super-resolution microscopy, enabling multiplexed and reversible labeling (Miyoshi et al., 2021). The tag’s solubility characteristics (≥71.08 mg/mL in DMSO, ≥107.2 mg/mL in ethanol, and ≥55.4 mg/mL in water at room temperature) allow for straightforward preparation and conjugation in diverse laboratory contexts [APExBIO].

Evidence & Benchmarks

• Monoclonal antibodies developed against the V5 tag exhibit fast dissociation kinetics (half-lives 0.98–2.2 s) while retaining high specificity, validated by single-molecule TIRF microscopy and immunoassays (Miyoshi et al., 2021).
• V5-tagged proteins are reliably detected by Western blot and immunoprecipitation in complex mammalian lysates, with minimal cross-reactivity (internal guide).
• The V5 tag (GKPIPNPLLGLDST) does not disrupt protein function in recombinant virus construction or protein expression systems (internal review).
• Peptide is supplied as a lyophilized solid, stable for >12 months at -20°C under desiccation (product documentation).
• Solubility benchmarks: ≥107.2 mg/mL in ethanol, ≥71.08 mg/mL in DMSO, ≥55.4 mg/mL in water at 20–25°C (APExBIO).

Compared to previous reviews, this article provides updated quantitative benchmarks and clarifies molecular mechanisms validated by single-molecule studies.

Applications, Limits & Misconceptions

The V5 Epitope Tag Peptide is used for:

• Protein detection and quantification by Western blotting, ELISA, or immunoprecipitation.
• Affinity purification of tagged proteins using anti-V5 antibody columns.
• Single-molecule and super-resolution imaging via fluorescently conjugated Fab fragments (Miyoshi et al., 2021).
• Construction of recombinant viruses and protein expression studies with minimal disturbance to protein function (internal guide).

For a scenario-driven discussion of troubleshooting and workflow optimization, see this guide, which this article extends by emphasizing kinetic and solubility parameters.

Common Pitfalls or Misconceptions

• The V5 tag does not confer purification capability without the use of specific affinity resins or anti-V5 antibodies.
• Overexpression of tagged proteins may occasionally lead to aggregation or altered localization, independent of the V5 tag sequence.
• The peptide is intended for research use only and is not validated for diagnostic or therapeutic applications (APExBIO).
• Background signal may occur if endogenous proteins share similar sequences in rare cell lines—sequence alignment is recommended before use.
• The tag’s small size does not guarantee invisibility to all functional domains; empirical validation is required for each fusion context.

Workflow Integration & Parameters

• Fusion strategy: The V5 tag can be cloned at the N- or C-terminus of a target gene using standard molecular biology techniques (e.g., PCR with V5-encoding primers).
• Expression systems: Compatible with bacterial, yeast, insect, and mammalian cell systems.
• Detection: Use high-affinity monoclonal anti-V5 antibodies for Western blotting, IP, or immunofluorescence. Primary antibody concentrations between 0.1–1 μg/mL are recommended for most applications (Miyoshi et al., 2021).
• Solubilization: Prepare the peptide at desired concentrations in DMSO, ethanol, or sterile water, respecting the maximum solubility limits at room temperature (APExBIO).
• Storage: Store lyophilized peptide desiccated at -20°C; reconstituted solutions are stable for several weeks at 4°C.

For extended imaging and multiplex labeling, see also this guide, which this article updates with peer-reviewed kinetic data.

Conclusion & Outlook

The V5 Epitope Tag Peptide (SKU A6005, APExBIO) is a validated, high-performance tool for protein tagging, detection, and purification in modern molecular biology. Atomic benchmarks for solubility, antibody specificity, and kinetic parameters support its use in advanced workflows, including super-resolution microscopy. As fast-dissociating antibodies and multiplex imaging methods advance, the V5 tag’s utility and compatibility will likely expand further (Miyoshi et al., 2021). For detailed protocol recommendations and product ordering, visit the V5 Epitope Tag Peptide product page.