Eos (also called EosFP) is a photoactivatable fluorescent protein (PAFP).
Contents
Discovery
Eos was isolated from the coral Lobophyllia hemprichii in a large-scale screen for PAFPs.
Properties
Eos undergoes an irreversible photoconversion in response to 390 nm light. Prior to this conversion, it exhibits a green emission peak at 516 nm. Following conversion, it has a red emission peak at 581 nm.
Wild-type Eos is a tetrameric protein. It has been modified to generate a monomeric form (referred to as mEos) that is more amenable for experiments involving labeling of a single molecule. Further improvements of mEos lead to mEos2 that is able to mature at 37 °C and can be used in mammalian cells. One drawback of mEos2 - the formation of oligomers at high concentrations - was resolved in the next generation of mEos: mEos3.1 & mEos3.2.
Applications
Like other PAFPs, Eos can be used to optically label single cells for subsequent analysis. Because Eos is available in monomeric forms, it can also be used to observe the kinetics and trafficking of single molecules as a fusion protein.