title: Coupling factor B is a component of the Fo proton channel of mitochondrial H+-ATPase.
abstract: Repeated extraction of bovine heart submitochondrial particles with ammonia and EDTA (AE) yields a preparation that is highly deficient in coupling factor B (FB). The activity of the thrice extracted particle (AE-P3) in ATP-driven NAD+ reduction by succinate and the 32Pi-ATP exchange activity were substantially stimulated, 8-fold and 5-fold, respectively, by purified FB. To decrease the basal activity of the particle further, the residual FB in AE-P3 was inactivated by treatment with the -SH reagent, 4-vinylpyridine. The resulting particle was depleted of F1 by treatment with 3.5 M NaBr. This particle was incorporated into asolectin liposomes alone and in the presence of added FB. Passive proton conduction in the FB-deficient proteoliposomes was negligible and restored in the presence of FB. The H+ conductance was inhibited extensively by oligomycin and partially by F1-ATPase. The results show absolute dependence on FB for functioning of the FO proton channel.
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001965:Bromides / Q000494:pharmacology; D002417:Cattle; D002458:Cell Fractionation; D007473:Ion Channels / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D008929:Mitochondria, Heart / Q000201:enzymology*; D025261:Mitochondrial Proton-Translocating ATPases; D009840:Oligomycins / Q000494:pharmacology; D010086:Oxidative Phosphorylation Coupling Factors; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D011522:Protons; D011725:Pyridines / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology; D017670:Sodium Compounds; D013367:Submitochondrial Particles / Q000201:enzymology
chemical_list: D001965:Bromides; D007473:Ion Channels; D008081:Liposomes; D009840:Oligomycins; D010086:Oxidative Phosphorylation Coupling Factors; D011522:Protons; D011725:Pyridines; D017670:Sodium Compounds; D000255:Adenosine Triphosphate; D012964:Sodium; D000251:Adenosine Triphosphatases; C032410:coupling factor B; D025261:Mitochondrial Proton-Translocating ATPases; D006180:Proton-Translocating ATPases; C029351:4-vinylpyridine; C027938:sodium bromide