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PDBsum entry 4ik9
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Fluorescent protein
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PDB id
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4ik9
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References listed in PDB file
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Key reference
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Title
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Structural insight into enhanced calcium indicator gcamp3 and gcampj to promote further improvement.
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Authors
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Y.Chen,
X.Song,
S.Ye,
L.Miao,
Y.Zhu,
R.G.Zhang,
G.Ji.
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Ref.
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Protein Cell, 2013,
4,
299-309.
[DOI no: ]
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PubMed id
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Abstract
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Genetically 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 β-barrel holes. Our study
proposes an efficient tool for mapping Ca(2+) signals in intact organs to
facilitate the further improvement of GCaMP sensors.
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