Abstract
Genetically encoded Ca2+ indicators (GECI) are important for the measurement of Ca2+in vivo. GCaMP2, a widely-used GECI, has recently been iteratively improved. Among the improved variants, GCaMP3 exhibits significantly better fluorescent intensity. In this study, we developed a new GECI called GCaMPJ and determined the crystal structures of GCaMP3 and GCaMPJ. GCaMPJ has a 1.5-fold increase in fluorescence and 1.3-fold increase in calcium affinity over GCaMP3. Upon Ca2+ binding, GCaMP3 exhibits both monomeric and dimeric forms. The structural superposition of these two forms reveals the role of Arg-376 in improving monomer performance. However, GCaMPJ seldom forms dimers under conditions similar to GCaMP3. St ructural and mutagenesis studies on Tyr-380 confirmed its importance in blocking the cpEGFP β-barrel holes. Our study proposes an efficient tool for mapping Ca2+ signals in intact organs to facilitate the further improvement of GCaMP sensors.
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Chen, Y., Song, X., Ye, S. et al. Structural insight into enhanced calcium indicator GCaMP3 and GCaMPJ to promote further improvement. Protein Cell 4, 299–309 (2013). https://doi.org/10.1007/s13238-013-2103-4
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DOI: https://doi.org/10.1007/s13238-013-2103-4