EosFP was first discovered in 2005 during a large scale screen for PAFPs (photoactivatable fluorescent proteins) within the stony coral Lobophyllia hemprichii.  It has since been successfully cloned in Escherichia coli and fusion constructs have been developed for use in human cells. Eos was named after the Greek goddess of dawn.
Unlike the tetrameric fluorescent proteins derived from anthozoan coral, which can interfere with normal cellular function due to interactions between protein subunits, EosFP has been broken up into dimeric and monomeric variants through the introduction of single point mutations. These variants have been successful in the tracking of cellular components without disturbing function in the host cell and maintain the same photophysical properties as wild-type Eos.
Since their discovery, monomeric Eos probes (mEos) have been shown to localize in the cytosol, plasma membrane, endosomes, prevacuolar vesicles, vacuoles, the endoplasmic reticulum, golgi bodies, peroxisomes, mitochondria, invaginations, filamentous actin and cortical microtubules. mEos fusion proteins allow for differential colour labelling in single cells, or groups of cells in developing organs.  They can also be used for the understanding of spatial/ temporal interactions between organelles and vesicles.  The two fluorescent forms of mEosFP (green and red) are compatible with CFP, GFP, YFP and RFP for multicolour labelling.