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Figure 2.
FIGURE 2. Structure and comparison of the Ca^2+ binding
EF-hands of ELC and CaM. A, octahedral coordination of Ca^2+ ion
in the first EF-hand of ELC showing an unusual closed
conformation. Ca^2+ is coordinated by Asp-15, Asp-17, Asp-19,
Lys-21, and two water molecules (red dots). Glu-26, which
normally provides a bidentate ligand for Ca^2+ in the open
state, is too far in the structure to participate in
coordination of the ion. B, comparison of the Ca^2+ binding
EF-hand I of the Physarum (red) and scallop myosins (blue;
Protein Data Bank accession code 1wdc) and the mutant CaM
structure (green; 1y6w) reveals high similarity between the
Physarum and the mutant CaM structure. Note the extra turn in
the first helix of scallop ELC. r.m.s. deviations of the
backbone carbons, after superimposing the scallop and calmodulin
structures, are 0.53 Å.
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