Parallel increases in amount of (3H)GDP binding and thermogenin antigen in brown-adipose-tissue mitochondria of cafeteria-fed rats.
In order to investigate the possible existence of a 'masked' (i.e. non-GDP-binding) form of thermogenin (the brown-adipose-tissue specific, 32 000 Da so-called "uncoupling" protein), rats were fed a routine pellet diet or, in addition to this, a cafeteria diet. Brown-adipose-tissue mitochondria isolated from the cafeteria-fed animals showed as expected an increased (3H)GDP binding capacity (from 0.26 to 0.41 nmol/mg protein; an increase of 57%). However, when analysed by a quantitative enzyme-linked immuno-assay system for thermogenin, the mitochondria also showed an increased content of thermogenin (from 14.9 to 20.5 micrograms per mg; an increase of 38%). The ratio between thermogenin and GDP binding was 61 000 and 53 000 g/mol in the two cases; these values were not significantly different and were in good agreement with suggestions that thermogenin binds 1 GDP per thermogenin dimer. It was concluded that under the conditions investigated, there was no reason to assume the existence of a masked form of thermogenin.
D002001:Adipose Tissue, Brown / Q000033:anatomy & histology / Q000378:metabolism*; D000818:Animals; D001835:Body Weight; D002352:Carrier Proteins / Q000032:analysis / Q000378:metabolism*; D004032:Diet; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019204:GTP-Binding Proteins; D006150:Guanine Nucleotides / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism*; D006801:Humans; D007473:Ion Channels; D008565:Membrane Proteins; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins; D009929:Organ Size; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism*; D000071256:Uncoupling Protein 1
D002352:Carrier Proteins; D006150:Guanine Nucleotides; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D011956:Receptors, Cell Surface; D000071256:Uncoupling Protein 1; D006153:Guanosine Diphosphate; D019204:GTP-Binding Proteins