INSR binds insulin and has a tyrosine protein kinase activity. The short isoform has a higher affinity for insulin. The receptor mediates the metabolic functions of insulin. The receptor binding to insulin stimulates association of the receptor with downstream mediators including IRS1 and phosphatidylinositol 3'-kinase (PI3K). Defects in INSR are the cause of insulin resistance.The synthetic peptide used to raise the antibody Cat. No. 200110 is selected from a sequence within the N-term region of human INSR. For blocking experiments, a 10 to 100 fold molar excess to antibody is recommended.