Uncoupling protein in embryonic brown adipose tissue--existence of nonthermogenic and thermogenic mitochondria.
Embryonic development of mouse and rat brown adipose tissue was characterized by electron microscopy and by quantifying the mitochondrial oxidative, phosphorylating and thermogenic capacities immunochemically, using antibodies against cytochrome oxidase, F1-ATPase and uncoupling protein, respectively. Mitochondria and cytochrome oxidase were detected from the 15-16th day of pregnancy and their amounts continuously increased toward birth. F1-ATPase was also found on the 15th day but it reached a maximum level already on the 19th day when the uncoupling protein appeared and rapidly increased during further maturation of brown adipose tissue. It thus appears that mitochondria in early prenatal brown adipose tissue lack completely uncoupling protein and are nonthermogenic. They transform into typical thermogenic mitochondria abruptly only 2 days before birth.
D002001:Adipose Tissue, Brown / Q000201:enzymology / Q000502:physiology* / Q000648:ultrastructure; D000818:Animals; D001833:Body Temperature Regulation; D002352:Carrier Proteins; D002454:Cell Differentiation; D003576:Electron Transport Complex IV / Q000302:isolation & purification; D004622:Embryo, Mammalian; D005314:Embryonic and Fetal Development; D007473:Ion Channels; D008565:Membrane Proteins / Q000302:isolation & purification / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008928:Mitochondria / Q000201:enzymology / Q000502:physiology*; D024101:Mitochondrial Proteins; D006180:Proton-Translocating ATPases / Q000302:isolation & purification; D051381:Rats; D011919:Rats, Inbred Strains; D000071256:Uncoupling Protein 1
D002352:Carrier Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D000071256:Uncoupling Protein 1; D003576:Electron Transport Complex IV; D006180:Proton-Translocating ATPases