Figure 3. Putative IGF-1R-associated accessory protein(s) augment GH signaling.
A) GH enhances association of GHR/JAK2 with IGF-1R and an IGF-1R-associated protein(s), “X”, augmenting GH signaling. “X” is cartooned as a transmembrane protein to suggest likely association with IGF-1R ECD and actions exerted intracellularly, but “X” could be a protein complex that either augments signaling or lessens down-regulation of signaling. B) In IGF-1R’s absence, GH does not induce “X” to join the GHR/JAK2 signaling complex and signaling is relatively diminished. CR-L2 region of IGF-1R ECD is shown in solid black and is envisioned as the region of IGF-1R that interacts with GHR. See the text for discussion.