For instance, one study developed a series of arylidene-imidazolones based on the GFP chromophore, which exhibited significant variations in fluorescence quantum yield depending on the solvent used.

“That indicated there must be some kind of coupling,” Morin said. Shimomura continued to study GFP and identified its chromophore in 1979. 4 Ultimately, though, he returned to studying bioluminescence ...

The ability of this protein to form a fluorescent chromophore in the absence of any additional factors has spurred wide applications of GFP as a genetically encoded marker and biosensor.