cAMP is a universal second messenger of many G-protein-coupled receptors and regulates
a wide variety of cellular events. cAMP exerts its effects via cAMP-dependent protein kinase
(PKA), cAMP-gated ion channels, and two isoforms of exchange protein directly activated by
cAMP (Epac). Here we report the development of novel fluorescent indicators for cAMP
based on the cAMP-binding domains of Epac and PKA. Fluorescence resonance energy
transfer between variants of green fluorescent protein (enhanced cyan fluorescent protein …