Fig. 2

Conformational rearrangement of GDF-5 upon complex formation. a Structural alignment of unbound (green) and GDF-5 R57A (blue/cyan) bound to BMPR-IA showing an induced fit rearrangement of the tips of finger 1 and 2 upon type I receptor binding. b As in (a) but viewed from the top. Upon binding to BMPR-IA, finger 1 and 2 of GDF-5 move towards the BMP type I receptor surface (shown as transparent van der Waals surface representation). c Stereoview of the conformational change of GDF-5 upon type I receptor binding. The side chain of Trp33 and Trp36 show the largest rearrangement, moving up to 10 Å. d Structural alignment of GDF-5 (wild-type) bound to BMPR-IB (magenta/rose) and GDF-5 R57A (blue/cyan) bound to BMPR-IA showing that the bound conformation of GDF-5 is almost identical irrespective of the type I receptor bound. e Different spatial requirements due to amino acid differences between BMPR-IA (black, only residues Glu81 to Gln94 are shown) and BMPR-IB (magenta ribbon plot) result in a small but significant bending of the α-helix 1 of GDF-5 (GDF-5 bound to BMPR-IA shown in cyan, GDF-5 bound to BMPR-IB colored in rose)