title: Mammalian ATPsynthase monomer versus dimer profiled by blue native PAGE and activity stain.
abstract: Studies into the effects of oligomerization on F(0)F(1)ATPsynthase function are contradictory. We optimized the in-gel ATPase assay to investigate the functional differences of monomers versus dimers. In Triton X-100 extracts of heavy bovine heart mitochondria (HBHM) and mitoplasts, but not submitochondrial particles (MgATP-SMP), dimers had greater specific activity than monomers: at 30 degrees C, the dimer/monomer activity ratios were 2.3, 1.4, and 1.0, respectively. These differences in HBHM and mitoplasts extracts were enhanced at 37 degrees C but lost at 20 degrees C. In mitoplasts but not in MgATP-SMP, dimers were selectively shielded from limited chymotrypsin degradation of F(1) alpha subunit, possibly due to interactions with other proteins or ligands in the native inner membrane. Despite these differences, all three preparations had similar percentages of dimers and similar contents of the native inhibitor IF(1) in Vm (monomer) and (dimer) Vd. These results suggest that, in native membrane, monomers and dimers are functionally distinct.
authors: Department of Biomedical Sciences and Technologies, University of Udine, Udine, Italy.
authors: Elena
authors: E
authors: Bisetto
authors: Francesca
authors: F
authors: Di Pancrazio
authors: Maria Paola
authors: MP
authors: Simula
authors: Irene
authors: I
authors: Mavelli
authors: Giovanna
authors: G
authors: Lippe
mesh_terms: D000818:Animals; D002417:Cattle; D004396:Coloring Agents; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods*; D008929:Mitochondria, Heart / Q000378:metabolism; D025261:Mitochondrial Proton-Translocating ATPases / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D004396:Coloring Agents; D025261:Mitochondrial Proton-Translocating ATPases