Structure
Two alpha subunits and two beta subunits make up the IGF-1 receptor. Both the α and β subunits are synthesized from a single mRNA precursor. The precursor is then glycosylated, proteolytically cleaved, and crosslinked by cysteine bonds to form a functional transmembrane αβ chain. The α chains are located extracellularly while the β subunit spans the membrane and are responsible for intracellular signal transduction upon ligand stimulation. The mature IGF-IR has a molecular weight of approximately 320 kDa. The receptor is a member of a family which consists of the Insulin Receptor and the IGF-2R (and their respective ligands IGF-1 and IGF-2), along with several IGF-binding proteins.
IGF-1R and IR both have a binding site for ATP, which is used to provide the phosphates for autophosphorylation (see below). There is a 60% homology between IGF-1R and the insulin receptor.
In response to ligand binding, the α chains induce the tyrosine autophosphorylation of the β chains. This event triggers a cascade of intracellular signaling that, while somewhat cell type specific, often promotes cell survival and cell proliferation.
Read more about this topic: Insulin-like Growth Factor 1 Receptor
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