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
Famous quotes containing the word structure:
“The question is still asked of women: “How do you propose to answer the need for child care?” That is an obvious attempt to structure conflict in the old terms. The questions are rather: “If we as a human community want children, how does the total society propose to provide for them?””
—Jean Baker Miller (20th century)
“There is no such thing as a language, not if a language is anything like what many philosophers and linguists have supposed. There is therefore no such thing to be learned, mastered, or born with. We must give up the idea of a clearly defined shared structure which language-users acquire and then apply to cases.”
—Donald Davidson (b. 1917)
“Slumism is the pent-up anger of people living on the outside of affluence. Slumism is decay of structure and deterioration of the human spirit. Slumism is a virus which spreads through the body politic. As other “isms,” it breeds disorder and demagoguery and hate.”
—Hubert H. Humphrey (1911–1978)