Abstract
Complexes formed between organic dyes and genetically encoded proteins combine the advantages of stable and tunable fluorescent molecules and targetable, biologically integrated labels. To overcome the challenges imposed by labeling with bright fluorescent dyes, a number of approaches now exploit chemical or environmental changes to control the properties of a bound dye, converting dyes from a weakly fluorescent state to a bright, easily detectable complex. Optimized, such approaches avoid the need for removal of unbound dyes, facilitate rapid and simple assays in cultured cells and enable hybrid labeling to function more robustly in living model organisms.