4ik3
High resolution structure of GCaMP3 at pH 8.5High resolution structure of GCaMP3 at pH 8.5
Structural highlights
FunctionK4DIE3_ENTQU GFP_AEQVI Energy-transfer acceptor. Its role is to transduce the blue chemiluminescence of the protein aequorin into green fluorescent light by energy transfer. Fluoresces in vivo upon receiving energy from the Ca(2+)-activated photoprotein aequorin. Publication Abstract from PubMedGenetically encoded Ca(2+) indicators (GECI) are important for the measurement of Ca(2+) 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 Ca(2+) 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 beta-barrel holes. Our study proposes an efficient tool for mapping Ca(2+) signals in intact organs to facilitate the further improvement of GCaMP sensors. Structural insight into enhanced calcium indicator GCaMP3 and GCaMPJ to promote further improvement.,Chen Y, Song X, Ye S, Miao L, Zhu Y, Zhang RG, Ji G Protein Cell. 2013 Apr;4(4):299-309. doi: 10.1007/s13238-013-2103-4. Epub 2013, Apr 3. PMID:23549615[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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