Red fluorescent proteins: chromophore formation and cellular applications

In the last decade, a number of red fluorescent proteins (RFPs) that emit orange, red, and far-red fluorescence have been isolated from anthozoans (corals), and developed through directed molecular evolution. An attractive property possessed by some RFPs is that their red fluorescence can be turned on or modulated by illumination at specific wavelengths. Recent progress in the development of RFPs has been accompanied with detailed studies of chromophore chemistry. A thorough understanding of the molecular mechanisms involved in the post-translational modifications of red chromophores would enable scientists to design RFPs with the desired properties to advance imaging applications. This article provides a broad perspective on the chemistry and applications of RFPs. ⺠RFPs emit orange, red, and far-red fluorescence in their final matured states. ⺠The maturation of a DsRed type chromophore proceeds via a blue-emitting intermediate. ⺠The photoconversion of a Kaede type RFP occurs via a β-elimination reaction. ⺠Superior RFPs will be required for use in deep-tissue and whole-body imaging. ⺠It is possible to design new RFPs with improved photochemical properties.