Uncoupling proteins are located in the inner mitochondria membrane. Their name is derived from their function: they uncouple oxidative processes of the respiratory chain from ATP synthesis. Hitherto several members of the family have been described, the best known being UCP1. UCP1 can be expressed exclusively in brown adipose tissue and it is responsible for the heat production. In humans the brown fat disappears during the early childhood. In adults another members of the UCP family can be found - UCP2 and UCP3. It is widely accepted that these proteins affect lipid metabolism and energy expenditure. They are intensively studied owing to their possible use in the therapy of obesity. However, their physiological function has not been yet fully established.

        Key words: uncoupling proteins, thermogenesis, oxidative phosphorylation, obesity.