[Characters of uncoupling protein and its relation with obesity]

Uncoupling proteins(UCP) are carrier proteins in mitochondria. In eukaryotic cells, ATP is generated by oxidative phosphorylation, an energetic coupling at mitochondria level. The oxidative reactions occurring in the respiratory chain generate an electrochemical proton gradient at both sides of the inner membrane of mitochondria. This gradient is used by the ATP synthase to phosphorylate ADP into ATP. The coupling of cell respiration with ADP phosphorylation is only partial in brown adipose tissue (BAT) mitochondria, where UCP causes a reentry of protons into the matrix and abolishes the electrochemical proton gradient. The liberated energy is then dissipated as heat and the synthesis of ATP is reduced. Recently, the cloning of new UCPs expressed in other tissues revealed the importance of this kind of regulation of respiratory control in metabolism and energy expenditure. The newly characterized UCPs are potential target drugs for obesity treatment, which could be favor of energy expenditure and diminish the metabolic efficiency.