Brown adipose tissue is a specialized thermogenic organ in newborns and hibernating mammals. Non-shivering thermogenesis in brown fat is mediated by a specific protein in the inner mitochondrial membrane. Which protein directly uncouples oxidative phosphorylation to generate heat?
- A Cytochrome c oxidase
- B ATP synthase
- C Uncoupling protein-1 (thermogenin) ✓
- D Carnitine palmitoyltransferase-1
Correct answer: C. Uncoupling protein-1 (thermogenin)
Explanation
Uncoupling protein-1 (UCP-1, thermogenin) in the inner mitochondrial membrane of brown adipose tissue dissipates the proton gradient, uncoupling oxidative phosphorylation so that energy is released as heat rather than stored as ATP. Cytochrome c oxidase and ATP synthase are part of normal oxidative phosphorylation. CPT-1 is involved in fatty acid transport, not thermogenesis.
Reference: Guyton and Hall Textbook of Medical Physiology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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