Ca2+-regulated photoproteins: structural insight into the bioluminescence mechanism.

The bioluminescent jellyfish has contributed two famous proteins to modern science: green fluorescent protein or GFP, which finds wide use as a probe in cell biology studies, and aequorin, which has been used for intracellular calcium measurement for more than 30 years. More recently, obelin, a protein from the bioluminescent hydroid and also in the family of what are called "Ca2+-regulated photoproteins", has been shown to have very attractive properties both in general applications and for basic structural biology investigations. This review will survey the new information into their molecular mechanism of bioluminescence action.