Well-characterized antibodies for epitope tags consisting of short sequences are widely used in the study of protein expression in various systems. The Nano-tag is a new streptavidin-binding peptide for both the purification and the detection of Nano-tagged proteins. This peptide possesses nanomolar-affinity for streptavidin and therefore is termed Nano-tag. The nano-tags have two types, Nano-tag15 (MDVEAWLGARVPLVET) and Nano-tag9 (MDVEAWLGAR), which bind to streptavidin with dissociation co