Choose the correct sequence of G protein coupled receptor activation

  1. Activated GPCR binds trimeric G-protein → interaction of G protein with receptor forms Gβγ → Gβγ binds and activates phospholipase C beta (PLCβ) → PLCβ catalyzes the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) to diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3) → IP3 opens calcium channels in the endoplasmic reticulum → cytosolic calcium ion levels increase → increased cytosolic calcium and DAG activate PKC
  2. Activated GPCR binds trimeric G-protein → interaction of G protein with receptor forms Gα-GTP → Gα-GTP binds and activates PLCβ → PLCβ catalyzes the hydrolysis of PIP2 to DAG and IP3 → DAG opens calcium channels in the endoplasmic reticulum → cytosolic calcium ion levels increase  → increased cytosolic calcium and IP3 activate PKC
  3. Activated GPCR binds trimeric G-protein → interaction of G protein with receptor forms Gα-GTP → Gα-GTP binds and activates PLCβ → PLCβ catalyzes the hydrolysis of PIP2 to DAG and IP3 → IP3 closes calcium channels in the endoplasmic reticulum → cytosolic calcium ion levels decrease → decreased cytosolic calcium and DAG activate PKC
  4. Activated GPCR binds trimeric G-protein → interaction of G protein with receptor forms Gα-GTP → Gα-GTP binds and activates PLCβ → PLCβ catalyzes the hydrolysis of PIP2 to DAG and IP3 → IP3 opens calcium channels in the endoplasmic reticulum → cytosolic calcium ion levels increase → increased cytosolic calcium and DAG activate PKC