Uncoupling Protein 1 (UCP1) is a protein found in the inner mitochondrial membrane of brown adipose tissue. Its primary function is to generate heat by dissipating the proton gradient created during cellular respiration, a process known as non-shivering thermogenesis. This helps maintain body temperature, especially in cold environments. UCP1 is activated by free fatty acids and plays a crucial role in energy expenditure. By allowing protons to flow back into the mitochondrial matrix without producing ATP, it converts energy into heat. This mechanism is particularly important for newborns and hibernating animals, which rely on it for thermoregulation.