The mRNA level of the circadian regulated Gonyaulax luciferase remains constant over the cycle.

The expression of luciferin-binding protein (LBP) and luciferase (LCF), two proteins that are involved in bioluminescence in Gonyaulax polyedra, is controlled by a cellular circadian clock. In the case of LBP, its temporal expression is reported to be regulated at the translational level, involving both 5' and 3' untranslated regions (UTRs) of lbp mRNA. Here, we show that the amounts of lcf mRNA are constant throughout the day-night cycle, indicating that the circadian expression of LCF is also regulated at the translational level.