Figure 4
BMP-2 type II receptor interface. (a) Location of the type II ligand/receptor binding epitopes on wildtype BMP-2 (left) and ActR-IIBECD(right). For designation of β-strands and finger-like structures see [62], the contact residues are marked in grey. (b) Surface representation of the type II ligand/receptor binding epitopes in the ''open book'' view. The surface of BMP-2 (left) is color coded by amino acid properties as follows: hydrophobic amino acids (A, F, G, I, L, M, P, V, W, Y) are shown in white/grey, polar residues in bright/dark green (H, N, Q, S, T), acidic residues in orange/red (D, E) and positively charged amino acids (K, R) in cyan/blue. Darker colors mark the contact interface. The surface of ActR-IIBECD (right) is color coded identically. (c) Contact scheme of the wildtype BMP-2:ActR-IIBECD interaction. Intermolecular van der Waals contacts (cutoff 4.5 Å) are marked by lines, H-bonds are shown in red. Contacts involving hydrophobic residues of BMP-2 are shown in the left panel, interactions involving polar residues of BMP-2 are on the right. The surface area (Å2) buried upon complex formation is indicated by small numbers.