Eirik Korsell wrote:
>Does anyone know if there is a higher concentration of UCP-1 and UCP-2
>(uncoupling proteins) in the average mouse cell compared to that same
>concentration in a human cell of the same type?
This is not known. However, there is clearly more uncoupling activity
(proton leak) in mitochondria and hepatocytes from smaller animals than
larger ones. See our papers on this subject (below) for more details. It
is not established that UCP-2 and other UCPs are the catalyst for this
natural uncoupling activity, although there are some suggestive experiments
that point that way.
Martin Brand
Brookes, P.S , Buckingham, J.A., Tenreiro, A.M., Hulbert, A.J. and Brand,
M.D. (1997) The proton permeability of the inner membrane of liver
mitochondria from ectothermic and endothermic vertebrates and from obese
rats: correlations with standard metabolic rate and phospholipid fatty acid
composition. Comp. Biochem. Biophys. In press
Rolfe, D.F.S. and Brand, M.D. (1997) The physiological significance of
mitochondrial proton leak in animal cells and tissues. Biosci. Rep. 17,
9-16
Porter, R.K., Hulbert, A.J. and Brand, M.D. (1996) Allometry of
mitochondrial proton leak: influence of membrane surface area and fatty
acid composition. Am. J. Physiol. 271, R1550-R1560
Rolfe, D.F.S. and Brand, M.D. (1996) Contribution of mitochondrial proton
leak to skeletal muscle respiration and to standard metabolic rate. Am. J.
Physiol. 271 (Cell Physiol. 40), C1380-C1389
Porter, R.K. and Brand, M.D. (1995) Causes of the differences in
respiration rate of hepatocytes from mammals of different body mass. Am.
J. Physiol. 269, R1213-R1224
Porter, R.K. and Brand, M.D. (1995) Cellular oxygen consumption depends on
body mass. Am. J. Physiol. 269, R226-R228
Brand, M.D., Chien, L.-F., Ainscow, E.K., Rolfe, D.F.S. and Porter, R.K.
(1994)
The causes and functions of mitochondrial proton leak. Biochim. Biophys.
Acta 1187, 132-139
Porter, R.K. and Brand, M.D. (1993) Body mass dependence of H+ leak in
mitochondria and its relevance to metabolic rate. Nature 362, 628-630
Martin D. Brand
Department of Biochemistry, University of Cambridge
Tennis Court Road, Cambridge CB2 1QW UK
phone: +44 1223 333648, fax: +44 1223 333345
Internet: http://www.bio.cam.ac.uk/dept/biochem/brand/
