Breen 2006 J Biol Chem

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Breen EP, Gouin SG, Murphy AF, Haines LR, Jackson AM, Pearson TW, Murphy PV, Porter RK (2006) On the mechanism of mitochondrial uncoupling protein 1 function. J Biol Chem 281:2114-9.

» PMID: 16291746 Open Access

Breen EP, Gouin SG, Murphy AF, Haines LR, Jackson AM, Pearson TW, Murphy PV, Porter RK (2006) J Biol Chem

Abstract: Native uncoupling protein 1 (UCP 1) was purified from rat mitochondria by hydroxyapatite chromatography and identified by peptide mass mapping and tandem mass spectrometry. Native and expressed UCP 1 were reconstituted into liposomes, and proton flux through UCP 1 was shown to be fatty acid-dependent and GDP-sensitive. To investigate the mechanism of action of UCP 1, we determined whether hydrophilic modification of the omega-carbon of palmitate effected its transport function. We show that proton flux was greater through native UCP 1-containing proteoliposomes when facilitated by less hydrophilically modified palmitate (palmitate > omega-methoxypalmitate > omega-hydroxypalmitate with little or no proton flux due to glucose-O-omega-palmitate or undecanesulfonate). We show that non-proton-dependent charge transfer was greater when facilitated by less hydrophilically modified palmitate (palmitate/undecanesulfonate > omega-methoxypalmitate > omega-hydroxypalmitate, with no non-proton-dependent charge transfer flux due to glucose-O-omega-palmitate). We show that the GDP-inhibitable oxygen consumption rate in brown adipose tissue mitochondria was reversed by palmitate (as expected) but not by glucose-O-omega-palmitate. Our data are consistent with the model that UCP 1 flips long-chain fatty acid anions and contradict the "cofactor" model of UCP 1 function.


O2k-Network Lab: IE Dublin Porter RK


Labels:


Organism: Rat 


Enzyme: Uncoupling protein 


HRR: Oxygraph-2k 

Spectrophotometry; Spectrofluorimetry