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Figure 3.
Figure 3. The Structure of CD47 in Complex with SIRPα
(A) The structure of CD47 (yellow ribbons) complexed with SIRPα
d1 (blue ribbons). Sites of N-linked glycosylation are shown as
magenta spheres. A schematic representation of the 5
transmembrane helix C-terminal domain of CD47 is shown,
including the proposed disulfide bond between C15 (Gly in our
structure; yellow sphere) and C245. The inset shows a close-up
view of the CD47/SIRPα interaction interface.
(B) The
structure of CD47 in complex with SIRPα (yellow) is almost
indistinguishable from that of CD47 solved in isolation (orange
and gray). Remarkably, the interaction of strand G with the rest
of the CD47 monomer is almost identical regardless of whether it
is strand swapped or not. The inset shows L101 and T102, which
mediate the turn at the tip of the FG loop in the
non-strand-swapped CD47 monomer.
(C) The surface of SIRPα
as viewed by CD47. The molecular surface of SIRPα d1 is shown,
colored by electrostatic potential. Regions of CD47 that
interact with SIRPα are shown as sticks. In (C) and (D), areas
of particular interest are identified by roman numerals (see
[E]) and loop/strand names are shown, with NA denoting the
N-terminal 6 residues of CD47.
(D) The surface of CD47 as
viewed by SIRPα. The molecular surface of CD47 is shown,
colored by electrostatic potential. Loops of SIRPα that
interact with CD47 are shown as sticks.
(E) Selected
portions of the interface. Residues of CD47 (yellow carbon
atoms) and SIRPα (blue carbon atoms) are shown as sticks, and
water molecules are shown as red spheres. The molecular surface
of SIRPα is shown (white, semitransparent). Hydrogen bonds and
salt bridges are shown as orange dashes. The roman numerals of
the panels identify the regions of the interaction on the
molecular surfaces in (C) and (D).
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