title: Functional characterization of an uncoupling protein in goldfish white skeletal muscle.
abstract: Uncoupling proteins (UCP) are able to increase H(+) leakage across the inner mitochondrial membrane, thus dissipating the membrane potential and increasing oxygen consumption. Despite the identification of several UCP orthologs in birds, reptiles, amphibians and fish, little is known about their functional properties in fish. The aim of this work was to identify and characterize a UCP in mitochondria found in goldfish white skeletal muscle. Western blot analysis, using a polyclonal antibody raised against mammalian UCP3, showed a single band at approximately 32 kDa. During non-phosphorylating respiration, we observed that palmitate promoted a dose-dependent increase in oxygen consumption that is abolished by addition of BSA (fatty acid chelator). Interestingly, this palmitate-induced increase in oxygen consumption was not inhibited by GDP, a well-known UCP inhibitor. In phosphorylating mitochondria, palmitate lowered both ADP/O ratio (number of atoms of phosphorus incorporated as ATP per molecule of O2 consumed) and the respiratory control ratio. Moreover, we found that different fatty acids can modulate mitochondrial membrane potential. In conclusion, our results suggest that goldfish UCP is functionally similar to the UCP found in other species, including mammals.
authors.affiliation: Laboratório de Adaptações Metabólicas, Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil.
authors.forename: Reinaldo Sousa
authors.initials: RS
authors.lastname: dos Santos
authors.forename: Flavia Letícia Martins
authors.initials: FL
authors.lastname: Peçanha
authors.forename: Wagner Seixas
authors.initials: WS
authors.lastname: da-Silva
mesh_terms: D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D029941:Fish Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D006054:Goldfish; D007473:Ion Channels / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D008931:Mitochondria, Muscle / Q000737:chemistry / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D009124:Muscle Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology*; D019308:Palmitic Acid / Q000494:pharmacology; D000071247:Uncoupling Protein 3
chemical_list: D004791:Enzyme Inhibitors; D029941:Fish Proteins; D007473:Ion Channels; D024101:Mitochondrial Proteins; D009124:Muscle Proteins; D000071247:Uncoupling Protein 3; D019308:Palmitic Acid