Draft: Thermogenin

Thermogenin is a protein found in the inner mitochondrial membrane in adipose tissue of some animals, such as human infants and bears. The presence of this protein allows protons to flow from the intermembrane space to the mitochondrial matrix. If a lot of this protein is present, it will decrease the rate of ATP synthesis but increase the rate of oxygen consumption, which is a measure of electron transport chain activity. This is because the proton gradient cannot form if they are allowed to flow back to the matrix and cannot be built up in the intermembrane pace. The proton gradient is what powers the synthesis of ATP through ATP synthase. Oxygen consumption will still increase though since the electron transport chain will continue to pump protons into the intermembrane space in an attempt to form a gradient. Thermogenin allows for heat production without the production of ATP, so it is important to babies and hibernating bears, which don’t require much ATP.