On contrary, recently generated mutants of GFP with yellow-shifted (YFP) and cyan-shifted (CFP) emission spectrum are highly stable and brighter, when compared to BFP.

YFP can be protonated on Tyr203 and this modifies its excitation spectrum 1,5. Protonated YFP, however, is not excited at 458 nm, and it has an emission peak identical to that of unprotonated YFP ...

More precisely, as each fluorophore has a unique excitation spectrum and a unique emission spectrum, each peaking at a specific wavelength, they can be distinguished by either their excitation ...