Which second messenger is generated by phospholipase C acting on PIP2, and directly causes calcium release from the endoplasmic reticulum?
- A Inositol 1,4,5-trisphosphate (IP3) ✓
- B Diacylglycerol (DAG)
- C Cyclic AMP (cAMP)
- D Cyclic GMP (cGMP)
Correct answer: A. Inositol 1,4,5-trisphosphate (IP3)
Explanation
PLC cleaves PIP2 into IP3 and DAG; IP3 binds IP3 receptors (ligand-gated Ca2+ channels) on the ER, releasing Ca2+ into the cytosol. DAG remains membrane-bound and activates protein kinase C. cAMP is generated by adenylyl cyclase via Gs. cGMP is generated by guanylyl cyclase and activates PKG.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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