Figure 3.

A cartoon showing putative conformations of IGF-1 C domain residues in a hormone:receptor complex. The receptor fragment is the same as shown in Figure 2. (A) Receptor-bound IGF-1 is shown in orange. IR L1 and CR domains are shown in gray and IGF-1R αCT in green. The proposed putative positions of IGF-1 C domain residues are shown as dashed orange lines. The alternative positioning of IGF-1 C domain residues is indicated by dashed black arrows. The cartoon was created in PyMol from the PDB ID 4XSS structure (43). (B) An overlay of the receptor- bound structure of IGF-1 (in orange, from the PDB ID 4XSS complex) and a crystal structure of human IGF-1 (in blue, from the PDG ID 1GZR structure). The disconnected C domain in the IGF-1 PDB ID 1GZR structure is due to a lack of electron density around positions 36 and 37 (44).