Mol. Biol. Evol. doi:10.1093/molbev/msp194 (2009)

Despite fluorescent proteins' ubiquity in research, scientists still don't know much about their natural function or evolution. David Gruber of the City University of New York and his collaborators analysed the sequences of 102 different fluorescent and non-fluorescent proteins to work out their evolutionary history.

They found that a central domain of the proteins that contains the chromophore — the part that determines the molecule's colour — is highly conserved, and that its evolution does not correlate with the evolution of fluorescent colour. The proteins' outer regions are highly variable yet track well with fluorescent-colour evolution. The authors say that understanding the evolutionary pressures on fluorescent proteins will provide insight into their natural role.