tdEosFP is a fluorescent protein that can be irreversibly photoconverted from an initial green fluorescent form to a red fluorescent form upon UV irradiation. It is an artificial derivative of the naturally occurring fluorescent protein encoded by the Lobophyllia hemprichii EosFP gene (GenBank:AY765217), consisting of a tandem dimer of the d2EosFP variant (which contains the mutation T158H) connected by a short, flexible linker. The green fluorescent form has an excitation peak of 506nm and an emission peak of 516nm, while the red fluorescent form has an excitation peak of 569nm and an emission peak of 581nm in vitro. (PMID:16613485).