Properties of the human long and short isoforms of the uncoupling protein-3 expressed in yeast cells.
Two splice variants of the human uncoupling protein-3 (UCP3L and UCP3S) are highly expressed in skeletal muscle. The properties of UCP3L and S have been compared to those of UCP1 in a heterologous yeast expression system under the control of the galactose promoter. Both UCP3 isoforms were found to strongly impair the coupling efficiency of respiring cells thus resulting in increased thermogenesis. The uncoupling properties of both UCP3L and S could be clearly demonstrated also in isolated yeast mitochondria both in terms of coupled respiration and in the capacity to polarize the inner membrane in conditions of limited substrate availability. Contrary to what was observed with mitochondria containing UCP1, millimolar GDP and ATP had little if any effect on the uncoupling activity of UCP3. A very marked uncoupling of whole cells and isolated mitochondria was observed at very low expression levels of UCP3S indicating that the short isoform is more active than the long one.
Hinz
W
W
Dept. of Metabolic and Cardiovascular Disease, Novartis Pharma AG, Basel, Switzerland.
Grüninger
S
S
De Pover
A
A
Chiesi
M
M
D002151:Calorimetry; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D005690:Galactose / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000494:pharmacology; D006801:Humans; D007473:Ion Channels; D008314:Malonates / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins; D010101:Oxygen Consumption / Q000187:drug effects; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D019802:Succinic Acid / Q000494:pharmacology; D000071256:Uncoupling Protein 1; D000071247:Uncoupling Protein 3
D002352:Carrier Proteins; D007473:Ion Channels; D008314:Malonates; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; C000604371:UCP1 protein, human; C000604392:UCP3 protein, human; D000071256:Uncoupling Protein 1; D000071247:Uncoupling Protein 3; D006153:Guanosine Diphosphate; C030290:malonic acid; D019802:Succinic Acid; D005690:Galactose