Evidence for unmasking of rat brown-adipose-tissue mitochondrial GDP-binding sites in response to acute cold exposure. Effects of washing with albumin on GDP binding.
Rats, previously acclimated to 29 degrees C, were moved into the cold (4 degrees C) for 2 h. Scatchard analysis of GDP binding to the brown-adipose-tissue mitochondria of these animals showed a 2.3-fold increase in the number of high-affinity sites and a 1.5-fold increase in the number of low-affinity sites compared with binding in animals maintained at 29 degrees C. Immunochemical determination showed no increase in the amount of mitochondrial uncoupling protein during this period. This strongly suggests an unmasking of existing GDP-binding sites before a detectable increase in synthesis of uncoupling protein can occur. Washing with albumin increased the number of GDP-binding sites of brown-adipose-tissue mitochondria from both warm-housed and cold-exposed animals to the same extent. This indicates that the effects of washing with albumin and cold exposure are independent and additive.
Gribskov
C L
CL
Henningfield
M F
MF
Swick
A G
AG
Swick
R W
RW
D002001:Adipose Tissue, Brown / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins; D003080:Cold Temperature; D006150:Guanine Nucleotides / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism*; D007473:Ion Channels; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D024101:Mitochondrial Proteins; D051381:Rats; D011919:Rats, Inbred Strains; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D000071256:Uncoupling Protein 1
D002352:Carrier Proteins; D006150:Guanine Nucleotides; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D000071256:Uncoupling Protein 1; D006153:Guanosine Diphosphate; D012710:Serum Albumin, Bovine