Figure 1.

Architecture of insulin and insulin-like growth factor-1 receptors. Insulin and IGF-1 receptors consist of two extracellular α-chains and two transmembrane β-chains. The α-subunits have binding sites for insulin and IGF-1, whereas the cytoplasmic kinase domain comprises major sites for tyrosine autophosphorylation that are crucial for receptor activation. The α- and β-subunits are connected together via disulfide linkages (Figure is adapted from reference[9]). IGF: Insulin-like growth factor.