title: Factor B is essential for ATP synthesis by mitochondria.
abstract: Factor B is a water-soluble protein, which is required for the coupled activity of the mitochondrial ATP synthase complex. Specific removal of factor B from well-coupled bovine heart submitochondrial particles (SMP) results in uncoupling and the loss of ATP-driven membrane potential formation and reverse electron transfer from succinate to NAD. Addition of recombinant human factor B (molecular mass 20,341 Da) to factor B-depleted SMP (AE-SMP) restores these properties [G.I. Belogrudov, and Y. Hatefi, (2002) J. Biol. Chem. 277, 6097-6103]. This paper shows that extraction and purification of ATP synthase complex (complex V) from bovine heart mitochondria results in extensive loss of factor B. Addition of recombinant human factor B to AE-SMP completely restores the lost oxidative phosphorylation and ATP-32P(i) exchange activities of the particles and increases the ATP-32P(i) exchange activity of complex V by 2.5-fold. These results further indicate that factor B is an essential component of the mammalian ATP synthase complex.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins; D002417:Cattle; D011415:Complement Factor B / Q000378:metabolism*; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism*; D008929:Mitochondria, Heart / Q000201:enzymology*; D025261:Mitochondrial Proton-Translocating ATPases; D010766:Phosphorylation; D013367:Submitochondrial Particles / Q000201:enzymology; D013379:Substrate Specificity
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; D011415:Complement Factor B; D000251:Adenosine Triphosphatases; D025261:Mitochondrial Proton-Translocating ATPases; C020439:oligomycin sensitivity-conferring protein