What is the Avi-Tag?

The Avi‑Tag is a short peptide tag of 15 amino acids. Its defined sequence is Gly-Leu-Asn-Asp-Ile-Phe-Glu-Ala-Gln-Lys-Ile-Glu-Trp-His-Glu.

When this sequence is genetically fused to either the N-terminus or C-terminus of a target protein, it functions as a specific recognition site for the biotin ligase enzyme (commonly BirA). BirA enzymatically attaches a single biotin molecule to the lysine residue within the Avi-Tag sequence — enabling site-specific, uniform biotinylation of the protein.

Because the Avi-Tag is small and the biotinylation occurs at a single, predictable site, the tag has minimal impact on the target protein’s structure and functionality — a major advantage over random or chemical biotinylation.

How Avi-Tag Technology Works

During cloning or expression vector construction, the DNA encoding the Avi-Tag sequence is fused in-frame to the gene of interest. The result: a recombinant fusion protein carrying the Avi-Tag at its end. www.rndsystems.com+1

Once expressed, the fusion protein is exposed to BirA, ATP and biotin (in vitro or in vivo), which leads to a highly specific reaction: biotin is covalently attached to the lysine in the Avi-Tag. Beta LifeScience+1

The biotinylated protein can then be purified, immobilized on streptavidin/avidin-coated surfaces, used in binding assays, diagnostics, or any application that leverages the extremely strong and specific biotin-avidin interaction.

Advantages of Using the Avi-Tag Sequence

Site-specific / uniform biotinylation — only one biotin per protein, on a well-defined site.

Minimal structural interference — because Avi-Tag is short (~15 aa), adding it usually doesn’t disrupt the native folding or function of the protein.

Consistent orientation and reproducibility — biotinylated proteins when immobilized (e.g. on streptavidin surfaces) adopt a uniform orientation; also lot-to-lot consistency is easier compared to random biotinylation.

Versatility — suitable for protein purification, detection, interaction studies, diagnostics, biosensors, immunoprecipitation, cell-surface assays, etc.

Common Applications of Avi-Tag / Avi-Tag Sequence

Recombinant protein purification — using high-affinity biotin-avidin binding for efficient isolation.

Protein–protein interaction studies — immobilized biotinylated proteins allow binding assays, surface-based detection, and screening of ligands/antibodies.

Diagnostics & biosensing — biotin-tagged proteins can be used in ELISA, flow cytometry, surface-plasmon resonance (SPR), immunoprecipitation, etc.

Cell biology / immunology research — for labeling, tracking, surface-binding studies, receptor/ligand interaction assays.

Drug screening and screening assays — using stable, site-specific tagged proteins for high-throughput screening, binding assays, etc.

Why Researchers Choose Avi-Tag (via Providers like Beta LifeScience)

Using an Avi-Tag ensures reproducible biotinylation and high-quality proteins — ideal for sensitive assays where consistency matters. With the precise avi tag sequence, researchers can rely on predictable behavior, minimal protein disruption, and strong biotin-avidin interactions.

Moreover, compared to chemical biotinylation (which may attach multiple biotins randomly and potentially alter protein activity), Avi-Tag offers clean, single-site labeling — enhancing assay sensitivity and reducing background noise.

For labs focusing on protein interactions, diagnostics, structural studies, or any workflow requiring tagged proteins with intact functionality — Avi-Tag is among the most effective, flexible, and widely accepted tools.

Conclusion

The avi tag sequence — Gly-Leu-Asn-Asp-Ile-Phe-Glu-Ala-Gln-Lys-Ile-Glu-Trp-His-Glu — is a small, powerful peptide tag that enables precise, site-specific biotinylation of proteins when fused genetically. Through biotinylation by BirA ligase, the resultant proteins become ideal for purification, detection, immobilization, interaction assays, and many other applications.