IGF-1 Receptor (IGF-1R)

The IGF-1 receptor (IGF-1R) is a cell-surface receptor tyrosine kinase. When insulin-like growth factor 1 (or an analog) binds, the receptor activates downstream pathways associated with cell growth, proliferation, and protein-synthesis (anabolic) signaling.

In research on IGF-1 analogs, a key variable is not just receptor binding but how much ligand is free to reach IGF-1R — circulating IGF-1 is largely held by binding proteins, so engineered analogs that evade those proteins present more free ligand to the receptor in laboratory models.