Brown adipose tissue (BAT) mediates non-shivering thermogenesis. The protein responsible for uncoupling the proton gradient from ATP synthesis is:

• A Uncoupling protein-1 (UCP-1/thermogenin) in the inner mitochondrial membrane ✓
• B ATP synthase F0 subunit in an uncoupled configuration
• C Cytochrome c oxidase producing heat instead of ATP
• D Adenine nucleotide translocator (ANT) in reverse mode

Explanation

UCP-1 (uncoupling protein-1, thermogenin) is a proton channel specifically expressed in the inner mitochondrial membrane of brown adipocytes. Activated by free fatty acids (released by sympathetic stimulation via beta-3 adrenoceptors and hormone-sensitive lipase), UCP-1 dissipates the proton electrochemical gradient as heat instead of driving ATP synthesis. This is the molecular basis of non-shivering thermogenesis, crucial for cold adaptation and neonatal heat production. ATP synthase produces ATP and does not function as an uncoupler. Cytochrome c oxidase transfers electrons to oxygen and does not produce heat directly. ANT exchanges ATP/ADP and its reverse mode does not mediate thermogenesis.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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