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. This antibody is against the alpha subunit.