A high-performance genetically encoded fluorescent indicator for in vivo cAMP imaging

Nat Commun. 2022 Sep 12;13(1):5363. doi: 10.1038/s41467-022-32994-7.


cAMP is a key second messenger that regulates diverse cellular functions including neural plasticity. However, the spatiotemporal dynamics of intracellular cAMP in intact organisms are largely unknown due to low sensitivity and/or brightness of current genetically encoded fluorescent cAMP indicators. Here, we report the development of the new circularly permuted GFP (cpGFP)-based cAMP indicator G-Flamp1, which exhibits a large fluorescence increase (a maximum ΔF/F0 of 1100% in HEK293T cells), decent brightness, appropriate affinity (a Kd of 2.17 μM) and fast response kinetics (an association and dissociation half-time of 0.20 and 0.087 s, respectively). Furthermore, the crystal structure of the cAMP-bound G-Flamp1 reveals one linker connecting the cAMP-binding domain to cpGFP adopts a distorted β-strand conformation that may serve as a fluorescence modulation switch. We demonstrate that G-Flamp1 enables sensitive monitoring of endogenous cAMP signals in brain regions that are implicated in learning and motor control in living organisms such as fruit flies and mice.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Coloring Agents
  • Diagnostic Imaging*
  • Green Fluorescent Proteins / genetics
  • HEK293 Cells
  • Humans
  • Mice
  • Second Messenger Systems*


  • Coloring Agents
  • Green Fluorescent Proteins