What are tandem fluorescent proteins primarily used for?

Tandem fluorescent proteins are primarily used for FRET (Förster Resonance Energy Transfer) applications because they are designed to work closely together, enabling the study of interactions between proteins at a molecular level. In FRET, when one fluorescent protein (the donor) is excited by a specific wavelength of light, it can transfer energy to a nearby second fluorescent protein (the acceptor) if they are in close proximity—usually within 1 to 10 nanometers. This energy transfer causes the acceptor to emit light of a different wavelength.

Using tandem fluorescent proteins enhances the sensitivity and accuracy of FRET measurements, as the two proteins can be optimized for spectral overlap and efficiency of energy transfer. This makes them invaluable tools for exploring protein-protein interactions, enabling researchers to visualize and quantify these interactions in living cells.

While other options might have their own applications in biological research, they do not specifically focus on the unique properties and applications associated with tandem fluorescent proteins as effectively as FRET does.