Fig. 5.

Receptor assembly paradigms of the TGFβ superfamily. (A) Full signaling complex structures from across the TGFβ superfamily: activin (PDB ID code 6MAC), TGFβ (PDB ID code 3KFD), and BMP (PDB ID code 2GOO) (8, 9). Type II and type I receptors are represented in orange and yellow, respectively, with mature ligands in blue. (B) Cartoon representation of the receptor surface complex with cis- and trans-receptor pairs labeled. (C) Distances are calculated from the center of mass for each receptor for cis- and trans-receptor combinations. (D) Schematic representation depicting half the signaling complex for the 3 receptor binding mechanisms of TGFβ family ligands.