AMP-activated protein kinase (AMPK) is called the 'energy sensor' of the cell. When activated by a high AMP:ATP ratio, which combination of metabolic effects is correct?

• A Activates acetyl-CoA carboxylase and increases malonyl-CoA to inhibit CPT-1
• B Activates mTORC1 to increase protein synthesis and gluconeogenesis
• C Activates HMG-CoA reductase to increase cholesterol synthesis
• D Inhibits acetyl-CoA carboxylase (fatty acid synthesis) and activates fatty acid oxidation, glycolysis; inhibits gluconeogenesis and protein synthesis ✓

Explanation

AMPK is activated when AMP rises (indicating energy deficit). It phosphorylates and inhibits acetyl-CoA carboxylase (ACC), reducing malonyl-CoA, which derepresses CPT-1 to allow fatty acid oxidation. AMPK simultaneously activates GLUT4 translocation for glucose uptake and glycolysis. It inhibits mTORC1 (suppressing anabolic protein synthesis), HMGR (cholesterol synthesis), and gluconeogenesis (via CRTC2 phosphorylation). Metformin and exercise activate AMPK.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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