Dual-color system for simultaneously monitoring intracellular Ca(2+) and ATP dynamics

Although Ca(2+) regulates energy metabolism through diverse pathways, there have been no methods to monitor both Ca(2+) dynamics and metabolic activity simultaneously. Here we report a novel system for simultaneously monitoring intracellular Ca(2+) and ATP levels using a blue-emitting photoprotein and a red-emitting beetle luciferase. Using this system, we monitored the dynamic changes simultaneously in both intracellular Ca(2+) and ATP levels during chondrogenesis. We have found that both intracellular Ca(2+) and ATP levels oscillated and their oscillations have a nearly antiphase relationship with each other. The dual-color monitoring system is useful for studying the relationship between Ca(2+) dynamics and energy metabolic pathways.