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Detecting cAMP‐induced Epac activation by fluorescence resonance energy transfer: Epac as a novel cAMP indicator
Author(s) -
Ponsioen Bas,
Zhao Jun,
Riedl Jurgen,
Zwartkruis Fried,
van der Krogt Gerard,
Zaccolo Manuela,
Moolenaar Wouter H,
Bos Johannes L,
Jalink Kees
Publication year - 2004
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/sj.embor.7400290
Subject(s) - förster resonance energy transfer , guanine nucleotide exchange factor , yellow fluorescent protein , chemistry , in vivo , biophysics , microbiology and biotechnology , protein kinase a , fluorescence , biochemistry , signal transduction , kinase , biology , gene , physics , quantum mechanics
Epac1 is a guanine nucleotide exchange factor for Rap1 that is activated by direct binding of cAMP. In vitro studies suggest that cAMP relieves the interaction between the regulatory and catalytic domains of Epac. Here, we monitor Epac1 activation in vivo by using a CFP–Epac–YFP fusion construct. When expressed in mammalian cells, CFP–Epac–YFP shows significant fluorescence resonance energy transfer (FRET). FRET rapidly decreases in response to the cAMP‐raising agents, whereas it fully recovers after addition of cAMP‐lowering agonists. Thus, by undergoing a cAMP‐induced conformational change, CFP–Epac–YFP serves as a highly sensitive cAMP indicator in vivo . When compared with a protein kinase A (PKA)‐based sensor, Epac‐based cAMP probes show an extended dynamic range and a better signal‐to‐noise ratio; furthermore, as a single polypeptide, CFP–Epac–YFP does not suffer from the technical problems encountered with multisubunit PKA‐based sensors. These properties make Epac‐based FRET probes the preferred indicators for monitoring cAMP levels in vivo .