uncoupling protein 1

Thermogenin (called uncoupling protein by its discoverers and now known as uncoupling protein 1, or UCP1) is a mitochondrial carrier protein found in 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 babies which would otherwise occur due to their high surface area-volume ratio. Recent findings indicate that the UCP1 protein plays a crucial role in thermogenesis by catalyzing the dissipative production of heat through protons derived from NADH and FADH2. These electron carriers are produced in the TCA cycle from the oxidation of acetyl-CoA, which comes from the breakdown of free fatty acids. Intriguingly, the acetyl-CoA products undergo a recycling process that facilitates their re-utilization, thereby sustaining the cycle known as the HEAT cycle.

==Structure== thumb|left|Structure of the human uncoupling protein The atomic structure of human uncoupling protein 1 UCP1 has been solved by cryogenic-electron microscopy. The structure has the typical fold of a member of the SLC25 family. UCP1 is locked in a cytoplasmic-open state by guanosine triphosphate in a pH-dependent manner, preventing proton leak.