Uncoupling protein

An uncoupling protein is a mitochondrial inner membrane protein that can dissipate the proton gradient before it can be used to provide the energy for oxidative phosphorylation.

There are five types known in mammals:

Uncoupling proteins play a role in normal physiology, as in cold exposure or hibernation, because the energy is used to generate heat (see thermogenesis) instead of producing ATP. However, other substances such as 2,4-dinitrophenol and CCCP also serve the same uncoupling function, and are considered poisonous. Salicylic acid is also an uncoupling agent and will decrease production of ATP and increase body temperature if taken in excess. Uncoupling proteins are increased by thyroid hormone, norepinephrine, epinephrine, and leptin.