Biochemical aspects of the uncoupling proteins: view from the chair

The discovery of nonshivering thermogenesis (NST) and its location in brown adipose tissue (BAT) in the 1950s to 1970s was soon followed by purification of the first uncoupling protein (UCP1) and later by cloning of the gene for UCP1 in 1985. The properties of UCP1 fully explained the long-known phenomenon of stimulated NST in BAT. An additional four 'uncoupling proteins' have been cloned in the last two years and are in search of phenomena they can explain. The four speakers in this first session of the symposium on uncoupling proteins reviewed biochemical properties of UCP1 and of three of the novel UCPs. Several suggested functions include mediation of the mitochondrial proton leak in tissues other than BAT, therefore a major role in energy expenditure, and protection against reactive oxygen species. Tools, techniques and information not yet available and for which further research is needed are reviewed.