Thermogenin
Thermogenin (called uncoupling protein by its discoverers and now known as uncoupling protein 1, or UCP1) is an uncoupling protein found in the of brown adipose tissue (BAT). It is used to generate heat by non-shivering thermogenesis, and makes a quantitatively important contribution to countering heat loss in neonates which would otherwise occur due to the high surface area-volume ratio.
UCPs are transmembrane proteins that decrease the proton gradient generated in oxidative phosphorylation. They do this by increasing the permeability of the inner mitochondrial membrane, allowing protons that have been pumped into the intermembrane space to return to the mitochondrial matrix. UCP1-mediated heat generation in brown fat uncouples the respiratory chain, allowing for fast substrate oxidation with a low rate of ATP production. UCP1 is related to other mitochondrial metabolite transporters such as the adenine nucleotide translocator, a proton channel in the that permits the translocation of protons from the mitochondrial intermembrane space to the . UCP1 is restricted to brown adipose tissue, where it provides a mechanism for the enormous heat-generating capacity of the tissue.
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