Although UCP2 and UCP3 are closely related to UCP1, UCP2 and UCP3 do not affect thermoregulatory abilities of vertebrates.[1] UCPs are positioned in the same membrane as the ATP synthase, which is also a proton channel. The two proteins thus work in parallel with one generating heat and the other generating ATP from ADP and inorganic phosphate, the last step in oxidative phosphorylation.[2] Mitochondria respiration is coupled to ATP synthesis (ADP phosphorylation) but is regulated by UCPs.[3]