Recombinant Mouse Insulin R/CD220 Protein, CF

The Insulin Receptor (gene name INSR, designated CD220) is a type I transmembrane glycoprotein in the Insulin/IGF Receptor family of receptor tyrosine kinases that share structural similarity and overlapping intracellular signaling events (1-3). The 1382 amino acid (aa) mouse Insulin R preproprotein is processed by proteolysis to remove the signal peptide and produce an extracellular alpha portion (aa 28-748), and an extracellular/transmembrane/cytoplasmic beta subunit (aa 753-1372) (4). The extracellular domain (ECD) contains two homologous globular domains separated by a cysteine-rich domain and followed by three fibronectin type III domains. The intracellular region contains insulin-receptor substrate (IRS) docking sites, the kinase domain, and a phosphotyrosine-containing linker region. The Mouse Insulin R ECD shares 96%, 99%, 94% and 94% aa sequence identity with human, rat, equine and canine Insulin R, respectively. Insulin R may homodimerize, or heterodimerize with the IGF-I receptor (1, 3, 4). All receptor combinations bind insulin, IGF-I or IGF-II, but with differing affinities (2-5). This system allows fine tuning of signaling pathways according to the concentrations of insulin, IGF-I and IGF-II, and expression of receptor subunits on the cell surface (2, 3). Insulin R signaling regulates glucose uptake and metabolism, but also contributes to cell growth, differentiation and apoptosis (2, 3, 5, 6). Consistent with mice deleted for Insulin R, mutations in the human Insulin R gene have been linked severe insulin resistance (type A and Rabson-Mendenhall syndrome) that may include type II diabetes mellitus and, rarely, leprechaunism (Donohue syndrome) that also includes growth delays and endocrine system abnormalities (1, 7).  The R&D Systems mouse Insulin R consists of the entire ECD and is a pre-receptor that does not contain bound insulin.