The mitochondrial uncoupling protein from guinea-pig brown adipose tissue. Synchronous increase in structural and functional parameters during cold-adaptation.
The time-course for the induction of the uncoupling pathway in the inner membrane of brown-fat mitochondria from cold-adapting guinea pigs was studied. The amount of the protein was quantified from the capacity for high-affinity binding of GDP to the intact mitochondria, and was compared with the functional parameters diagnostic of the protein, namely the nucleotide-sensitive proton conductance and the sensitivity to uncoupling by low concentrations of fatty acids. A monophasic increase in nucleotide titre was observed, with no evidence of an early 'unmasking' of preexisting nucleotide-binding sites. The nucleotide-sensitive conductance increased in precise synchrony with the nucleotide-binding capacity. Mitochondria from newborn animals, and those from acutely cold-adapted animals, showed anomalously low sensitivities to uncoupling by fatty acids.
D000222:Adaptation, Physiological; D002001:Adipose Tissue, Brown / Q000378:metabolism*; D000367:Age Factors; D000818:Animals; D002352:Carrier Proteins; D003080:Cold Temperature; D006153:Guanosine Diphosphate / Q000494:pharmacology; D006168:Guinea Pigs; D007473:Ion Channels; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000378:metabolism*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D024101:Mitochondrial Proteins; D010101:Oxygen Consumption; D011522:Protons; D000071256:Uncoupling Protein 1
D002352:Carrier Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D011522:Protons; D000071256:Uncoupling Protein 1; D006153:Guanosine Diphosphate