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Figure 5.
A rationally designed, improved GCaMP2 variant. A,
fluorescence excitation (solid lines) and emission (dashed
lines) spectra of Ca^2+-saturated GCaMP2 T116V (red) and
T116V/D381Y (blue), as well as their calcium-free forms (gray
and black, respectively). Normalized absorbance spectra of each
are shown in the inset. B, close-up stereo view of the
Ca^2+-saturated monomeric GCaMP2 structure, showing the location
of aspartate 381 (D381) of CaM at the CaM/cpEGFP domain
interface. GCaMP2 is displayed as ribbons colored by domain. The
side chain of Asp^381 and the cpEGFP chromophore are displayed
as sticks. A model of a tyrosine side chain at position 381 is
shown in semitransparent sticks to represent a possible
conformation of the D381Y mutant and to illustrate the proximity
of this side chain to the chromophore.
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