IGFR-1 and Insulin Receptor

    • Insulin-like growth factor family includes two growth factors (IGF-1, IGF-2) and two receptors (IGF-1R, IGF-2R).
    • IGF-1 and IGF-2 are polypeptide hormones structurally similar to insulin. IGF-IR, IGF-2R, and insulin receptors are also structurally similar and are able to form heterodimers.
    • IGF-1R is activated by IGF-1, IGF-2, and insulin and has a strong growth-promoting effect.
    • IGF-2R does not trigger signaling, but regulates extracellular IRS-2 levels through receptor-mediated endocytosis and degradation. Upon phosphorylation, IGF-1R recruits and phosphorylates adaptor proteins IRS-1 (insulin receptor substrate), IRS-2, and SHC.
    • IRS-1 acts as a second messenger within , ELK1, GSK3) via PI3K and RAS pathways and also initiates the translocation of glucose transporter (GLUT) to the cell surface where it facilitates transport of glucose into the cell.
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