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Figure 1.
Figure 1. Structure of Apo Human ApyraseRibbon diagram of
the human apyrase propeller structure as viewed along (A) or
perpendicular to (B) the central tunnel. The sheets are numbered
1 to 5 and organized sequentially in a counterclockwise
direction, and the four antiparallel β strands within each
sheet are denoted a to d in the order from axis to perimeter.
The β propeller is circularized by juxtaposition of the 1a and
1b strands. The polypeptide chain is colored from blue at the N
terminus through to red at the C terminus. The Ca^2+ ion (green
sphere) is located in the middle of the central tunnel.(C)
Superposition of the α carbon traces of the five blades of the
human apyrase propeller. Blades 2 and 5 (green and light blue)
have the shortest loops between β strands. Blades 1, 3, and 4
(gray, yellow, and pink) have at least one long loop projecting
from the top face of the β propeller.(D) Stereoview of the
2F[o] − F[c] electron density map (contoured at 1.5σ) showing
the coordination geometry of the Ca^2+ ion (green sphere)
connecting the five blades of the human apyrase propeller. Water
molecules are shown as red spheres, and calcium coordinations
are denoted by dotted lines.(E) Sequence alignment of the five
blades of the human apyrase propeller. The approximate
boundaries of the β strands are highlighted. φ designates
conserved hydrophobic residues.
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