ABSTRACT
Among the vast number of uorescent proteins (FPs) engineered from molecules discovered in various marine organisms, a set of FPs have been developed with distinct optical properties in that they are capable of pronounced changes in their chromophore structure or conformation within the protein and consequently their spectral properties in response to irradiation with light of a specic wavelength and intensity. Here, a general term, optical highlighter, is used to broadly describe these proteins, which are initially nonuorescent or can be made nonuorescent at the excited uorescent wavelength and increase in uorescence with contrast over a darker background upon light irradiation. These optical highlighting properties have been discovered in wild-type proteins or have been introduced into FPs by mutating selected residues in or near their chromophores to change their spectral properties and responses to light irradiation. Optical highlighter FPs have proved to be excellent tools for the precise optical labeling and tracking of proteins in cellular systems. They offer an alternative to photobleaching approaches in the study of protein kinetics, gene expression, organelle dynamics, and even cellular dynamics within living specimen. Moreover, optical highlighter FPs have stimulated the development of super-resolution microscopy techniques to provide key information about cellular structure and function that is otherwise unattainable.
