The AVI Tag Sequence has become a go-to tool in protein research. Scientists add this short peptide to their target proteins to enable precise biotin labeling. This simple addition opens doors to better purification, detection, and interaction studies.
Many labs rely on the AVI Tag Sequence because it allows controlled biotin attachment without disrupting protein function. The tag’s design ensures biotin links to just one spot. Researchers use it for everything from basic experiments to advanced assays.
Understanding the AVI Tag Sequence helps you choose the right tagging method for your work. Let’s break down its structure, what it does, and practical steps to use it.
What Is the AVI Tag Sequence?
The AVI Tag Sequence is a 15-amino-acid peptide with a specific order. Its sequence is GLNDIFEAQKIEWHE.
This short chain gets fused to either the N-terminus or C-terminus of a target protein. The key feature lies in the lysine (K) residue near the end. That single lysine accepts biotin during an enzymatic reaction.
The AVI Tag Sequence comes from optimized peptide libraries. It works with the E. coli biotin ligase enzyme called BirA. BirA recognizes this exact sequence and attaches biotin to the lysine in the presence of biotin and ATP.
The Order of the AVI Tag Sequence
The full AVI Tag Sequence follows this precise order: Gly-Leu-Asn-Asp-Ile-Phe-Glu-Ala-Gln-Lys-Ile-Glu-Trp-His-Glu.
Each position matters for recognition by BirA. The sequence starts with glycine and ends with glutamic acid. The central lysine serves as the biotin attachment site.
- Position 1: Gly (Glycine)
- Position 2: Leu (Leucine)
- Position 3: Asn (Asparagine)
- Position 4: Asp (Aspartic acid)
- Position 5: Ile (Isoleucine)
- Position 6: Phe (Phenylalanine)
- Position 7: Glu (Glutamic acid)
- Position 8: Ala (Alanine)
- Position 9: Gln (Glutamine)
- Position 10: Lys (Lysine – biotin site)
- Position 11: Ile (Isoleucine)
- Position 12: Glu (Glutamic acid)
- Position 13: Trp (Tryptophan)
- Position 14: His (Histidine)
- Position 15: Glu (Glutamic acid)
This order ensures high specificity. BirA ignores other lysines in the protein and targets only this one.
Meaning and Benefits of the AVI Tag Sequence
The AVI Tag Sequence means reliable, site-specific biotinylation. Biotin binds strongly to avidin or streptavidin. This interaction powers many applications in research.
Key benefits include:
- Precise control over biotin placement, avoiding random labeling that can harm protein activity.
- Minimal impact on protein folding or function due to the tag’s small size (only 15 amino acids).
- High efficiency, often exceeding 95% biotinylation in vitro with BirA.
- Versatility for in vivo or in vitro labeling in bacteria, mammalian cells, or other systems.
- Strong, stable binding for purification, immobilization, or detection assays.
Researchers value the AVI Tag Sequence for consistent results. It supports studies on protein interactions, signaling pathways, and more.
How to Use the AVI Tag Sequence?
Using the AVI Tag Sequence starts with cloning. Add the tag DNA sequence to your protein’s gene.
Common steps include:
- Design your expression vector with the AVI Tag Sequence at the N- or C-terminus. Include a linker if needed to avoid steric issues.
- Express the fusion protein in a suitable host, such as E. coli co-expressing BirA for in vivo biotinylation.
- For in vitro labeling, purify the protein first, then incubate with BirA, biotin, and ATP under mild conditions.
- Verify biotinylation using streptavidin-based detection, such as Western blot or ELISA.
- Apply the biotinylated protein in your assay, like affinity purification on avidin columns or immobilization on plates.
Many commercial vectors include the AVI Tag Sequence. You can choose flexible or rigid linkers between the protein and tag for better access.
Common Applications of the AVI Tag Sequence
Labs use the AVI Tag Sequence in various ways. It excels in protein purification by binding to streptavidin beads. This method captures tagged proteins gently and specifically.
In interaction studies, biotinylated proteins pair with streptavidin-coated surfaces for SPR, BLI, or pull-down assays. The tag also supports MHC-tetramer production for T-cell staining.
Detection becomes straightforward too. Streptavidin conjugates with HRP or fluorophores reveal the protein in blots or microscopy.
The AVI Tag Sequence fits drug screening, structural biology, and functional analysis. Its reliability makes it a favorite over chemical biotinylation methods.
Tips for Successful Use of the AVI Tag Sequence
Placement matters. N-terminal tags sometimes work better for certain proteins, while C-terminal suits others. Test both if possible.
Add linkers to improve biotin access. Short flexible ones (like GGGS) or extended rigid ones help in many cases.
Check expression levels and biotin efficiency early. Overexpression can sometimes reduce labeling rates.
Use fresh reagents for in vitro reactions. Mild temperatures (around 30°C) boost BirA activity.
Always confirm the AVI Tag Sequence remains intact after cloning. Sequence verification prevents errors.
Conclusion
The AVI Tag Sequence offers a smart way to biotinylate proteins with precision. Its defined order—GLNDIFEAQKIEWHE—ensures BirA targets the right spot every time. This leads to clean, functional biotinylated proteins ready for purification, detection, or binding studies.
Whether you work in academic research or industry, the AVI Tag Sequence simplifies complex experiments. It keeps protein activity high while providing strong biotin-avidin bonds.
If you need custom AVI-tagged proteins or help with biotinylation projects, reach out to our team. We handle design, expression, and validation to save you time. Contact us today to discuss your next protein project.
