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Figure 1.
Figure 1. Crystal Structures of GCaMP2•Ca^2+ and cpEGFP
(A) Domain organization of GCaMP2 and truncated
derivatives. A schematic presentation of the GCaMP2 fusion
protein is shown. The color scheme introduced here is maintained
throughout the article. Residue numbering for circularly
permutated EGFP (cpEGFP) and GCaMP2ΔRSET follows the sequence
of GCaMP2.
(B) Crystal structure of the isolated cpEGFP
moiety. The C-terminal fragment of C-EGFP is colored in light
green, and the N-terminal fragment is colored in dark green. Two
orthogonal views are shown.
(C) Crystal structure of
monomeric GCaMP2ΔRSET in its Ca^2+-bound state. Crystals were
grown in the presence of 1 mM Ca^2+. Two orthogonal views are
shown. The M13 helix is shown in blue, and the calmodulin (CaM)
domain is shown in red. The cpEFGP is colored as described in
(B).
(D) Comparison of crystal structures of GCaMP2,
cpEGFP, and GFP-S65T. Distance difference matrices based on Cα
positions were used to compare the conformation of cpEGFP in
isolation (bottom-right triangle) and as part of GCaMP2
(top-left triangle) with the structure of GFP-S65T (PDB code
1EMA; see Supplemental Experimental Procedures). Difference
matrices were regularized using a Z-score analysis and
color-coded accordingly. Each entry in the matrix depicts the
difference in distance between corresponding Cα atoms in the
two structures. Distances that show little change are blue. Red
entries represent distances that are significantly different in
the two structures.
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