Insulin-like growth factor 1 receptor (IGF1R) system. Ligands (IGF-I, IGF-II, and insulin) bind to the receptors (IGF1R, IGF-2R, and insulin receptor [IR]) with different affinity. The IGF1R and IR possess tyrosine kinase activity. Binding of the IGF-1 ligand to IGF1R leads to a conformational modification of the receptor and activation of the tyrosine kinase subunit. Each receptor triggers complex and different intracellular signaling cascades.
