The AVI Tag is a commercially developed 15-amino acid peptide tag consisting of GLNDIFEAQKIEWHE. This unique peptide is readily and specifically biotinylated by the E. coli biotin ligase, BirA, and Avi-tagged proteins can be detected or purified by avidin or streptavidin. Antibodies against the Avi epitope are also available, allowing for immunological detection or investigation of Avi-tagged recombinant proteins.