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Phosphoinositide GPCR Signaling quiz

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  • What is the main type of GPCR involved in the Phosphoinositide GPCR signaling pathway?
    The main GPCR is the alpha adrenergic GPCR, which differs from the beta adrenergic GPCR used in the adenylate cyclase pathway.
  • Which G protein subtype is activated in the PSP pathway?
    The G protein subtype activated is Gq, which is a heterotrimeric G protein with alpha, beta, and gamma subunits.
  • What is the effector enzyme in the PSP pathway?
    The effector enzyme is phospholipase C (PLC), which hydrolyzes PIP2 to generate secondary messengers.
  • What is the substrate for PLC in the PSP pathway?
    The substrate for PLC is phosphatidylinositol 4,5-bisphosphate (PIP2), a glycerophospholipid found in the membrane.
  • Name the three secondary messengers produced in the PSP pathway.
    The three secondary messengers are inositol 1,4,5-trisphosphate (IP3), diacylglycerol (DAG), and calcium ions (Ca2+).
  • What does IP3 do after it is produced in the PSP pathway?
    IP3 diffuses to the endoplasmic reticulum and binds to calcium channels, causing the release of Ca2+ into the cytoplasm.
  • How does DAG function in the PSP pathway?
    DAG remains in the membrane and, together with Ca2+, activates protein kinase C (PKC) to help trigger the cell response.
  • What is the role of calcium ions released by IP3 in the PSP pathway?
    Calcium ions activate calmodulin, which then activates other protein kinases, contributing to the cell response.
  • What is the final enzyme activated by DAG and Ca2+ in the PSP pathway?
    The final enzyme is protein kinase C (PKC), which phosphorylates targets to help generate the cell response.
  • What triggers the initial activation of the PSP pathway?
    The pathway is triggered by the binding of a hormone ligand, such as epinephrine, to the alpha adrenergic GPCR.
  • What happens to the Gq alpha subunit after GPCR activation?
    The Gq alpha subunit exchanges GDP for GTP, dissociates from the beta and gamma subunits, and activates PLC.
  • How are IP3 and DAG generated in the PSP pathway?
    PLC hydrolyzes PIP2, splitting it into IP3 (which diffuses into the cytoplasm) and DAG (which stays in the membrane).
  • What is the function of calmodulin in the PSP pathway?
    Calmodulin, activated by Ca2+, helps activate other cytosolic protein kinases that contribute to the cell response.
  • How is the PSP pathway reset after signaling?
    The Gq alpha subunit hydrolyzes GTP to GDP, reassociates with beta and gamma subunits, and the ligand dissociates from the GPCR.
  • What mnemonic story is used to help remember the PSP pathway steps?
    The story features 'Alpha Hero' (Gq alpha), 'Pip' (PIP2), 'Police' (PLC), 'Dagger' (DAG), 'Ice Picks' (IP3), and 'Captain Marvelous' (Ca2+/calmodulin) to represent key pathway components and events.