Clone REA271 recognizes human CD221 (IGF-1R), a widely expressed cell-surface glycoprotein composed of two α subunits and two β subunits. 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 subunits span the membrane and are responsible for intracellular signal transduction upon ligand stimulation. IGF-1R is activated by binding of its ligands insulin-like growth factor 1 (IGF-1), IGF-2, as well as insulin to the extracellular α subunits. Ligand binding leads to autophosphorylation of tyrosine residues in the cytoplasmic regions of the receptor β subunits and subsequent recruitment and phosphorylation of insulin receptor substrate (IRS) proteins. This finally results in activation of the PI3K/Akt and MAPK pathways, which mediate cell proliferation and survival. Many tumors and transformed cells exhibit altered IGF-1R expression.

Additional information: Clone REA271 displays negligible binding to Fc receptors.