Roles attributed to the different UCPs according to experimental methods

MethodDemonstrated or proposed roles
LiposomeProton leakProton leakProton leak
YeastProton leakProton leakProton leak
Transgenic miceRespiration uncouplingNot determinedProton leak or not
Increased oxidation
–/–miceRespiration uncouplingATP increase or notRespiration uncoupling or not
ThermogenesisROS scavengingROS scavenging
Insulin secretion
Normal animalsCold-induced thermogenesisROS scavengingROS scavenging
Insulin secretionT3 thermogenesis
Diet-induced thermogenesisDiet-induced thermogenesis
Fatty acid oxidationFatty acid oxidation
Human geneticsBody fat contentResting metabolic rateResting metabolics rate
Body fat content
Anorexia nervosaAnorexia nervosa
  • Transgenic mice refer to animals overexpressing UCP. Most biochemical studies supported a proton transport activity and a potential uncoupling activity of the UCPs. However, contrary to UCP1, analysis of normal mice or mice made null for Ucp2 or Ucp3 did not confirm the respiration uncoupling activity of UCP2 or UCP3.