Phospholipase C cleaves PIP2 into IP3 and diacylglycerol. While IP3 releases calcium from the endoplasmic reticulum, the fate of diacylglycerol is to:

• A Diffuse to the nucleus and inhibit gene transcription
• B Be converted to arachidonate exclusively by cyclooxygenase
• C Remain in the membrane and activate protein kinase C along with calcium and phosphatidylserine ✓
• D Serve as a direct ligand for intracellular steroid receptors

Explanation

Diacylglycerol is lipophilic and stays embedded in the plasma membrane. There, together with the calcium released by IP3 and membrane phosphatidylserine, it activates protein kinase B, which phosphorylates serine/threonine residues on target proteins. Option B is wrong because DAG is cleaved by phospholipase A2 to release arachidonic acid; cyclooxygenase then acts on arachidonate, not on DAG itself. This dual-arm design lets one hormone signal through both calcium and kinase pathways simultaneously.

Reference: Lehninger Principles of Biochemistry, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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