Blue fluorescent protein is a monomeric blue fluorescent protein generated by site-specific and random mutagenesis of TagRFP. TagBFP exhibits bright blue fluorescence with excitation/emission maxima at 402 and 457 nm, characterized by high photostability and extremely high pH-stability.
Compared to EBFP2, TagBFP is more then 1.8 times brighter, much more pH-stable and has twice shorter maturation half-time at 37°C. Narrow fluorescence emission peak of TagBFP provides for accurate and easy spectral separation with cyan and green fluorescent proteins and makes it a preferable tag for multicolor labeling. Good overlap between the emission spectrum of TagBFP and the absorbance spectra of TagGFP allows using these two proteins as a FRET pair.