Fig. 2: Comparison of ALK1 binding sites in binary and ternary BMPRII receptor complexes.

a Overlay of BMP10:ALK1 from the ternary signalling complex (cpx1, magenta, cpx2, purple) to those from binary complexes (PDB code 6SF1 in grey; 6SF3 in cyan for BMP10 and orange for ALK1). The backbones of all overlaid molecules are shown in ribbon. BMP10 from 6SF3 also shown in semi-transparent cartoon. Because in both 6SF1 and 6SF3, there was only one copy of BMP10:ALK1 monomer in an asymmetric unit, the dimeric receptor complexes for 6SF1 and 6SF3 were generated with a symmetry-related molecule and the two BMP10:ALK1 interfaces in 6SF1 and 6SF3 dimer would be identical. b Comparison of the buried surface area at the BMP10 and ALK1 interface in binary and ternary receptor complexes. c Overlay of all ALK1 chains, displayed in ribbon on BMP10 surface (light cyan). Four parts of BMP10 binding sites on ALK1 identified previously¹³ are highlighted by dashed lines. The colour for each chain is shown below. d Zoomed-in views of ALK1 H87 and E59 interaction area. H-bond interactions are shown with dotted lines. Same colour scheme as in c. The only interactions can be seen are in grey (from 6SF1), and orange and cyan (from 6SF3). Detailed information and the list of the interactions can be found in Supplementary Table 2.