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bioRxiv · 10.1101/2020.11.12.380089

Far-red fluorescent genetically encoded calcium ion indicators

Dalangin, R.·Drobizhev, M.·Molina, R. S.·Aggarwal, A.·Patel, R.·Abdelfattah, A. S.·Zhao, Y.·Wu, J.·Podgorski, K.·Schreiter, E. R.·Hughes, T. E.·Campbell, R. E.·Shen, Y.
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Abstract

Genetically encoded calcium ion (Ca2+) indicators (GECIs) are widely-used molecular tools for functional imaging of Ca2+ dynamics and neuronal activities on a single cell level. Here we report the design and development of two new far-red fluorescent GECIs, FR-GECO1a and FR-GECO1c, based on the monomeric far-red fluorescent protein mKelly. We characterized these far-red GECIs as purified proteins and assessed their performance when expressed in cultured neurons. FR-GECOs have excitation and emission maxima at ~ 596 nm and ~ 644 nm, respectively, display large responses to Ca2+ ({Delta}F/F0 = 6 for FR-GECO1a, 18 for FR-GECO1c), and are bright under both one-photon and two-photon illumination. FR-GECOs also have high affinities (apparent Kd = 29 nM for FR-GECO1a, 83 nM for FR-GECO1c) for Ca2+, and they enable sensitive and fast detection of single action potentials in neurons.

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Dalangin, R., Drobizhev, M., Molina, R. S., Aggarwal, A., Patel, R., Abdelfattah, A. S., Zhao, Y., Wu, J., Podgorski, K., Schreiter, E. R., Hughes, T. E., Campbell, R. E., Shen, Y.. 2020-11-15. Far-red fluorescent genetically encoded calcium ion indicators. https://doi.org/10.1101/2020.11.12.380089

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