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Recap of Insulin Signaling As A Growth Factor quiz

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  • What type of receptor does insulin bind to in order to initiate growth factor signaling?
    Insulin binds to the insulin receptor, which is a receptor tyrosine kinase (RTK).
  • What is the immediate effect of insulin binding to its receptor?
    Insulin binding causes autophosphorylation of the receptor, fully activating it.
  • Which substrate is phosphorylated by the activated insulin receptor?
    The insulin receptor phosphorylates insulin receptor substrate 1 (IRS-1) on tyrosine residues.
  • What adaptor protein binds to phosphorylated IRS-1, and through which domain?
    Grb2 binds to phosphorylated IRS-1 using its SH2 domain.
  • Which protein does the SH3 domain of Grb2 interact with in the insulin signaling pathway?
    The SH3 domain of Grb2 binds to the guanine exchange factor SOS.
  • What is the role of SOS in the insulin signaling pathway?
    SOS acts as a guanine exchange factor, facilitating the exchange of GDP for GTP on RAS, thereby activating it.
  • What happens to RAS after it is activated by GTP binding?
    Activated RAS initiates a MAP kinase cascade by activating RAF1.
  • Which kinase does RAF1 activate in the MAP kinase cascade?
    RAF1 phosphorylates and activates MEK.
  • What is the next step after MEK is activated in the signaling cascade?
    Activated MEK phosphorylates and activates ERK.
  • Where does ERK translocate after activation, and what is its function?
    ERK moves into the nucleus to regulate transcription factors involved in cell growth.
  • How is the insulin signaling pathway terminated?
    Signal termination occurs via phosphatases that remove phosphate groups and by GTP hydrolysis on RAS, accelerated by GAP proteins.
  • What is the function of GAP proteins in the insulin signaling pathway?
    GAP proteins accelerate the GTPase activity of RAS, promoting its inactivation and helping terminate the signal.
  • Why is the regulation of the insulin signaling pathway important for the cell?
    It ensures proper control of anabolic reactions and cell growth, preventing uncontrolled proliferation.
  • What mnemonic story was suggested to help remember the order of insulin signaling components?
    The story involves IRS1 giving a tax refund, ordering Grubhub, adding hot sauce, activating a rash, calling Dr. Raf, and making the irking pain go away.
  • What do the red arrows in the signaling diagram represent?
    The red arrows indicate the removal of phosphate groups by phosphatases, which helps terminate the signal.