UC San Diego

We report the design and generation of a fluorescence resonance energy transfer (FRET) reporter system tailored to sense changes in membrane potential. The FRET reporter consists of two fluorescence proteins: cyan fluorescence protein Cerulean with minimized dipole-moment and yellow fluorescence protein mCitrine with maximized dipole- moment. While Cerulean is membrane-localized by lipidating two opposite ends of the protein, mCitrine is lipidated only at its N-terminal. We hypothesize that in response to membrane potential change, mCitrine moves near and far from the plasma membrane, altering the amount of FRET ratio that provides a reasonable proxy for detecting changes in membrane potential. Our preliminary tests suggest that our system is functional and that it could potentially be further optimized to report electrical activities in neuronal cells.