A variety of substrate carrier proteins that are involved in energy transfer are found in the inner mitochondrial membrane. Such proteins include: ADP,ATP carrier protein (ADP/ATP translocase); 2-oxoglutarate/malate carrier protein; phosphate carrier protein; tricarboxylate transport protein (or citrate transport protein); Graves disease carrier protein; yeast mito- chondrial proteins MRS3 and MRS4; yeast mitochondrial FAD carrier protein; and many others.The brown fat uncoupling protein (UCP) dissipates oxidative energy into heatby transporting protons from the cytosol into the mitochondrial matrix.UCP functions as a dimer, forming a proton channel that leads to uncouplingof oxidative phosphorylation by dissipation of the electrochemical potentialacross the inner membrane.The protein has a tripartite structure, with 3 similar ~100 residue domains.The domains exhibit striking conservation of several residues, especiallyof glycine and proline, which may constitute structurally strategicpositions. The protein is thought to contain 6 transmembrane helices. These characteristics are shared by the ADP/ATP carrier protein, whichis a member of the mitochondrial carrier family.