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Figure 3.
Figure 3. Structure of KChIP1*-Kv4.2N30(A) Stereo cylinder
view of KChIP1* monomer showing the coordination of four
EF-hands (helix 2 to 5, N lobe, in cyan; helix 6 to 9, C lobe,
in blue) and the central groove bound by H10 (yellow) and α1
(red) helices. α1 is bent at Pro10. The N-terminal helix (H1)
is shown in yellow.(B) Stereo view of the KChIP1*-Kv4.2N30
dimeric complex, which is 90° rotated around the horizontal
axis from view A. The 2-fold axis lies at the center of the
dimer and perpendicular to the paper. The molecules are colored
in the same way as (A). The residues 21–30 of Kv4.2N30 lacking
electron density are not shown. Dots represent residues
160–170 of KChIP1* that lack electron density. Calcium ions
(spheres) are bound to EF-3 and EF-4.(C) Comparison of the loops
from four EF-hands of KChIP1*. Canonical Ca^2+-coordinating
positions are numbered (Figure 1A). Five out of seven
Ca^2+-coordinating oxygens (red) are from side chains of four
conserved residues (position 1, 3, 5, 12) and one from a
backbone carboxy-group (position 7). Calcium-loaded EF-3 and
EF-4 have an extra oxygen from water molecule. Position 1 of
EF-1 is not shown because it is part of helix (E1). Blue atoms
are nitrogens.
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