Is there a Life in the Cold without UCP1? Uncoupling Proteins Thermogenesis and Thermoregulatory

The original uncoupling protein UCPI (thermogenin) is only found in brown adipose tissue which is only found in mammals. UCPI is supposed to be the molecular basis for nonshivering thermogenesis. This tenet can be tested in the UCP I-ablated mice now available. Basically the results from investigation of these mice are very clear: there is no other mammalian nonshivering thermogenesis than that emanating from adrenergic stimulation of brown adipose tissue. No other proteins. not even the closely related UCP2 and UCP3, can take over as thermogenic proteins, even in the absence of UCP!.