Entacmaea quadricolor

Petersen J, Wilmann PG, Beddoe T, Oakley AJ, Devenish RJ, Prescott M, Rossjohn J (2003) The 2.0-A crystal structure of eqFP611, a far red fluorescent protein from the sea anemone Entacmaea quadricolor. J Biol Chem 278 44626-44631... 

Loos DC, Habuchi S, Flors C, Hotta J, Wiedenmann J, Nienhaus GU, Hofkens J (2006) Photoconversion in the red fluorescent protein from the sea anemone Entacmaea quadricolor is cis-trans isomerization involved J Am Chem Soc 128 6270-6271... 

More than 50 crystal structures of GFP, GFP mutants, and GFP analogs have been deposited in the protein databank [53], and of these two have their chromophore s oriented in a trans configuration. They are the intensely colored blue nonfluorescent pocilloporin pigment [54], which has a distinctly nonplanar trans configuration with most of the deviation from planarity occurring due to q> rotation, and a GFP-like protein from the sea anemone, Entacmaea quadricolor (eqFP611) [55]. 

In 2002 Labas and co-workers investigated numerous Anthozoan species and were able to clone 11 new fluorescent proteins with colors ranging from green to red [34]. An additional protein (eqFP611) emitting far-red light was isolated and cloned from Entacmaea quadricolor another anthozoan species [35]. 

A new red protein eqFP611 from Entacmaea quadricolor displayed both monomeric and tetrameric features in initial studies [78]. FCS analysis at low nmol/1 concentrations predicted a mass ratio of 2.7 between DsRed and eqFP611 and produced a diffusion coefficient similar to the monomeric GFP mutant Citrine. In contrast, size-exclusion chromatography and the recently resolved crystal structure of eqFP611 indicated that eqFP611 too can form tetramers... 

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