AviTagBirA

AviTagBirA refers to the combination of the AviTag peptide and the BirA biotin ligase, a system used to achieve site-specific biotinylation of proteins. The AviTag is a short peptide that serves as a substrate for BirA, and the lysine within the tag is biotinylated, enabling precise labeling of the protein of interest. This approach is widely used in molecular biology and biotechnology to facilitate downstream applications that rely on biotin-streptavidin interactions.

Mechanistically, BirA recognizes the AviTag in the presence of biotin and ATP and transfers biotin to a specific lysine residue within the tag. This reaction can occur in vitro with purified BirA and substrates, or in vivo by co-expressing BirA in cells that produce the AviTag-fused protein. The result is a covalently modified protein carrying a biotin moiety at a defined location, enabling uniform labeling.

Applications of AviTagBirA span affinity purification, detection, and imaging. Biotinylated proteins can be captured on streptavidin-coated surfaces or detected with streptavidin conjugates, supporting quantitative assays, immobilization for assays, and imaging in research contexts. The system is valued for its small tag size, relative stability, and the ability to achieve uniform biotinylation without broad surface labeling.

Practical considerations include tag placement (N- or C-terminus or in permissive internal sites), potential effects on protein function, and the need to express BirA and supply biotin. Variants and related technologies exist, including engineered BirA variants for specialized labeling and proximity labeling approaches; however, AviTagBirA is primarily associated with site-specific biotinylation of fusion proteins for reliable downstream applications.