Photoaffinity labelling of the mitochondrial uncoupling protein by [3H]azido fatty acid affects the anion channel.
Brown adipose tissue (BAT) mitochondria were incubated with the azido derivative of fatty acid (hexadecanoic) containing four tritium atoms, [3H]AzHA, and among all mitochondrial proteins only a few proteins were photolabelled after irradiation with UV. It suggests the existence of specific fatty acid binding sites on mitochondrial proteins. It was also possible to label with [3H]AzHA the isolated uncoupling protein (UcP) of BAT mitochondria with a low stoichiometry--lower than one AzHA per dimeric UcP. These results together with the observed competition (i.e. prevention of photolabelling) of various UcP anionic substrates with [3H]AzHA and its dodecanoic acid analogue, suggest the existence of the specific fatty acid binding site on UcP identical with the anion channel or anion translocating site.
Růzicka
M
M
Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Borecký
J
J
Hanus
J
J
Jezek
P
P
D002001:Adipose Tissue, Brown / Q000378:metabolism*; D000345:Affinity Labels / Q000138:chemical synthesis; D000476:Alkanesulfonates / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002352:Carrier Proteins / Q000378:metabolism*; D006224:Cricetinae; D007473:Ion Channels / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D008647:Mesocricetus; D008928:Mitochondria / Q000737:chemistry / Q000378:metabolism*; D024101:Mitochondrial Proteins; D010169:Palmitic Acids / Q000138:chemical synthesis / Q000378:metabolism; D011506:Proteins / Q000032:analysis / Q000378:metabolism; D013229:Stearic Acids / Q000378:metabolism; D014316:Tritium; D014466:Ultraviolet Rays; D000071256:Uncoupling Protein 1
C098967:16-(4-azido-2-nitrophenylamino)hexadecanoic acid; D000345:Affinity Labels; D000476:Alkanesulfonates; D002352:Carrier Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D010169:Palmitic Acids; D011506:Proteins; D013229:Stearic Acids; D000071256:Uncoupling Protein 1; D014316:Tritium