The fluorescent protein color palette.

Advances in fluorescent protein development over the past 10 years have led to fine-tuning of the Aequorea victoria jellyfish color palette in the emission color range from blue to yellow, while a significant amount of progress has been achieved with reef coral species in the generation of monomeric fluorescent proteins emitting in the orange to far-red spectral regions. It is not inconceivable that near-infrared fluorescent proteins loom on the horizon. Expansion of the fluorescent protein family to include optical highlighters and FRET biosensors further arms this ubiquitous class of fluorophores with biological probes capable of photoactivation, photoconversion, and detection of molecular interactions beyond the resolution limits of optical microscopy. The success of these endeavors certainly suggests that almost any biological parameter can be investigated using the appropriate fluorescent protein-based application.