Insulin-Like Growth Factor I Receptor, Recombinant, Mouse (IGF-I Receptor, IGFIR, IGFR, Insulin-like

The insulin-like growth factor I receptor (IGF-I R or IGF1R, designated CD221) is a 450kD disulfide-linked heterotetrameric transmembrane glycoprotein consisting of two 130kD a and two 95kD b subunits (1, 4). The IGF-1 R cDNA encodes a preproreceptor that is proteolytically cleaved to produce the extracellular a subunit (aa31-737), which contains a cysteine-rich region and two ligand-binding fibronectin type III (FN-III) domains, and the b subunit (aa742-1369), which contains an extracellular FN-III domain, transmembrane and cytoplasmic tyrosine kinase domains (1). Extracellular portions of mature mouse IGF-I R share 99.7% aa identity with rat, 96% with human, canine and porcine, and 95% with bovine and equine IGF-I R. IGF-I R is expressed in all cell types and tissues. It binds insulin-like growth factor I (IGF- I) with high affinity, IGF-II with lower affinity, and insulin with lowest affinity (2, 3). Both IGF-I R and the structurally similar insulin receptor (Ins R) activate the same signaling pathways in response to their respective ligands (3). IGF-I R/Ins R hybrids are formed in proportion to their expression and respond primarily to IGF-I, probably down-regulating cellular response to insulin (2, 5). IGF signaling is also modulated by IGF binding proteins and the scavenger receptor, IGF-II R (4). Expression or glycosylation of IGF-I R may be altered in cancer cells (4, 5). Mice lacking IGF-I R show intrauterine growth deficiency and die at birth due to respiratory failure, and IGF-I R mutations in humans can retarded pre- and postnatal growth (6-8). IGF-I and its receptor are particularly important for neurogenesis, with deficiency producing microcephaly and learning disorders (9 -11). Low expression of IGF-I R enhances lifespan in both mouse and human by increasing resistance to oxidative stress (12, 13). IGF-I R expression in human embryonic stem cells is important for their survival and clonogenicity (14). Source: Recombinant corresponding to aa1-93 of mouse IGF-IR, fused with 6-His tag at C-terminal, expressed with CHO cells. Molecular Weight: ~104.5kD (single chain) 80.7kD (a subunit) 23.2 kD (b subunit), Endotoxin Level: <1EU/1ug (LAL), Biological Activity: Measured by its binding ability in a functional ELISA. When rmIGF-IR is present at 0.5ug/ml, the concentration of rmIGF-I that produces 50% of the optimal binding response is found to be ~25-100ng/ml. Storage and Stability: Lyophilized powder may be stored at -20°C. Stable for 12 months at -20°C. Reconstitute with PBS. Aliquot to avoid repeated freezing and thawing. Store at -20°C. Reconstituted product is stable for 6 months at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.