Crystal structure of OSCAR D1D2. (A) Crystal structure of
free OSCAR D1D2, colored according to secondary structure
(β-sheet, magenta; 310 helix, silver; polyproline-type
II helix, cyan). Putative N-glycosylation sites are shown as spheres.
Strands are labeled according to standard immunoglobulin-like domain
topology. (B) Overlay of D1 of apo-OSCAR (magenta) and THP-bound OSCAR
(cyan) to illustrate the shift of the C′ strand in the free
receptor (residues 47-55, PLLFRDVSS; shown as sticks) to a D strand in
the bound receptor. (C) Overlay of D1 from the collagen-binding LRC
receptors OSCAR (magenta), GPVI (blue), and LAIR-1 (green). (D) Overlay
of D2 from OSCAR (magenta), GPVI (blue), LILRB4 (orange), and p58-CL42
KIR (brown) to illustrate changes in the AB loop region and the
cis vs trans conformation of
residue Pro-111 (see supplemental Discussion).