Mitochondrial uncoupling proteins (UCP) are members of the larger family of mitochondrial anion carrier proteins (MACP). Uncoupling proteins separate oxidative phosphorylation from ATP synthesis with energy dissipated as heat, also referred to as the mitochondrial proton leak. Uncoupling proteins facilitate the transfer of anions from the inner to the outer mitochondrial membrane and the return transfer of protons from the outer to the inner mitochondrial membrane. They also reduce the mitochondrial membrane potential in mammalian cells. This gene is widely expressed in many tissues with the greatest abundance in brain and testis. Alternative splicing results in multiple transcript variants. A pseudogene of this gene has been defined on chromosome 4. [provided by RefSeq, Aug 2013].