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Free Radic Biol Med. 2007 Nov 15;43(10):1351-71. Epub 2007 Aug 24.

Mitochondrial uncoupling proteins--what is their physiological role?

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Department of Biomedical Sciences, Faculty of Medicine and Medical Sciences, University of Balamand, P.O. Box: 100 Tripoli, Lebanon.


The physiological functions of the mitochondrial uncoupling proteins (UCP2 and UCP3) are still under debate. There is, however, ample evidence to indicate that, in contrast to UCP1, they are not crucial for nonshivering thermogenesis and do not catalyze the basal proton conductance of mitochondria. Rather, there is good evidence that they increase mitochondrial proton conductance when activated by superoxide, reactive oxygen species derivatives such as hydroxynonenal, and other alkenals or their analogues. This review critically examines the evidence of the different proposed mechanisms for UCPs functions, namely (a) to export fatty acid anions from mitochondria, (b) to regulate insulin secretion in pancreatic beta-cells, and (c) to cause mild uncoupling and so diminish mitochondrial superoxide production, hence protecting against oxidative damage. Beside, available scientific data on UCP4 and UCP5/BMCP1 will be reviewed. However, their physiological function has not yet been established.

[Indexed for MEDLINE]

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