%A Yingxiao Chen, Xianqiang Song, Sheng Ye, Lin Miao, Yun Zhu, Rong-Guang Zhang, Guangju Ji %T Structural insight into enhanced calcium indicator GCaMP3 and GCaMPJ to promote further improvement %0 Journal Article %D 2013 %J Protein Cell %J Protein & Cell %@ 1674-800X %R 10.1007/s13238-013-2103-4 %P 299-309 %V 4 %N 4 %U {https://journal.hep.com.cn/pac/EN/10.1007/s13238-013-2103-4 %8 2013-04-01 %X

Genetically encoded Ca2+ indicators (GECI) are important for the measurement of Ca2+in vivo. GCaMP2, a widelyused 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.