Which protein mediates heat generation in brown adipose tissue during non-shivering thermogenesis?

Which protein mediates heat generation in brown adipose tissue during non-shivering thermogenesis?

• A. ATP synthase.
• B. UCP1 uncouples oxidative phosphorylation to release heat.
• C. Collagen.
• D. Lipoprotein lipase.

Answer: (B)

Non-shivering thermogenesis in brown fat relies on a protein that uncouples the normal flow of energy in mitochondria to generate heat. This protein, Uncoupling Protein 1 (UCP1), sits in the inner mitochondrial membrane and uncouples oxidative phosphorylation from ATP production by allowing protons to leak back into the matrix without driving ATP synthase. The energy from this proton leak is released as heat, warming the body. Cold exposure activates the sympathetic nervous system, releasing norepinephrine that promotes lipolysis and increases fatty acids, which help activate UCP1. In contrast, ATP synthase would normally use the proton gradient to make ATP, so it isn’t the mediator of heat in this pathway. Collagen is a structural protein, and lipoprotein lipase acts on circulating lipids but does not directly produce thermogenesis in brown fat.

Non-shivering thermogenesis in brown fat relies on a protein that uncouples the normal flow of energy in mitochondria to generate heat. This protein, Uncoupling Protein 1 (UCP1), sits in the inner mitochondrial membrane and uncouples oxidative phosphorylation from ATP production by allowing protons to leak back into the matrix without driving ATP synthase. The energy from this proton leak is released as heat, warming the body. Cold exposure activates the sympathetic nervous system, releasing norepinephrine that promotes lipolysis and increases fatty acids, which help activate UCP1. In contrast, ATP synthase would normally use the proton gradient to make ATP, so it isn’t the mediator of heat in this pathway. Collagen is a structural protein, and lipoprotein lipase acts on circulating lipids but does not directly produce thermogenesis in brown fat.