A cAMP Sensor Based on Ligand-Dependent Protein Stabilization

[Image: see text] cAMP is a ubiquitous second messenger with many functions in diverse organisms. Current cAMP sensors, including Föster resonance energy transfer (FRET)-based and single-wavelength-based sensors, allow for real time visualization of this small molecule in cultured cells and in some cases in vivo. Nonetheless the observation of cAMP in living animals is still difficult, typically requiring specialized microscopes and ex vivo tissue processing. Here we used ligand-dependent protein stabilization to create a new cAMP sensor. This sensor allows specific and sensitive detection of cAMP in living zebrafish embryos, which may enable new understanding of the functions of cAMP in living vertebrates.