Architecture of the Fab:receptor complex of AbD1556:BMPR-IAEC.
(A) Ribbon representation of the Fab:receptor complex of BMPR-IA bound to AbD1556. The receptor ectodomain (Pro34 - Val118) is shown in green, the heavy chain of AbD1556 is shown in cyan, the light chain of the Fab is marked in magenta. Complementary determining regions (CDRs), constant and variable regions are indicated. (B) As in (A) but rotated by 150° around the y-axis. (C) Structural alignment of the four Fab:BMPR-IA complexes of the asymmetric unit. The four structures of BMPR-IAEC are shown in different shades of green, similarly the Fab heavy and variable regions of the four Fab molecules of the asymmetric unit are indicated in different shades of cyan and magenta. Only the Cα-trace is shown. Structural superposition was performed using all Cα-atoms of the four Fab molecules thereby showing slight, but significant differences in the location of the four BMPR-IA molecules (∼1 Å). (D) As in (C) but structural alignment was performed on the Cα-atoms of BMPR-IA. (E) As in (C) but side chains of the four BMPR-IA molecules of the asymmetric unit are shown, illustrating the positional shifts of the BMPR-IA molecules in the Fab binding site. (F) As in (E) but with structural alignment performed on the Cα-atoms of the four BMPR-IA molecules.
