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Query: EC:3.6.3.14 (ATP synthase)
 7,042 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies showed that Ca2+ induced monomer to active dimer interconversion of a mitochondrial ATPase inhibitor protein from bovine heart or rat skeletal muscle (Yamada, E.W., Huzel, N.J. and Dickison, J.C. (1981) J. Biol. Chem. 256, 10203-10207). Initial equilibrium dialysis measurements of Ca2+ binding showed that this unique protein possesses three binding sites of high affinity with a maximum of one mol of Ca2+ bound/mol of protein monomer. Magnesium (1 mM) did not affect the first association constant but increased the second and third by about 1.2 and 1.5 fold, respectively. That the apparent association constants varied with concentration of protein monomer was in agreement with the self-associating nature of the protein. Scatchard plots at three concentrations of protein intersected at a molar ratio of about 0.5 (Ca2+/monomer). Ka1 and Ka2 values of 4.2 microM and 12.1 microM, respectively, were estimated by extra-polation of apparent constants to infinite dilution of protein. Ka3 (51.3 microM) was estimated by extrapolation of double reciprocal plots of apparent constants versus protein concentration to infinite levels of protein. A model for Ca2+ binding by this self-associating protein is described. Trifluoperazine had no effect on the activity of the inhibitor protein from either tissue.
Cell Calcium 1985 Dec
PMID:Ca2+-binding properties of a unique ATPase inhibitor protein isolated from mitochondria of bovine heart and rat skeletal muscle. 293 56

The precursor of porin, a mitochondrial outer membrane protein, competes for the import of precursors destined for the three other mitochondrial compartments, including the Fe/S protein of the bc1-complex (intermembrane space), the ADP/ATP carrier (inner membrane), subunit 9 of the F0-ATPase (inner membrane), and subunit beta of the F1-ATPase (matrix). Competition occurs at the level of a common site at which precursors are inserted into the outer membrane. Protease-sensitive binding sites, which act before the common insertion site, appear to be responsible for the specificity and selectivity of mitochondrial protein uptake. We suggest that distinct receptor proteins on the mitochondrial surface specifically recognize precursor proteins and transfer them to a general insertion protein component (GIP) in the outer membrane. Beyond GIP, the import pathways diverge, either to the outer membrane or to translocation contact-sites, and then subsequently to the other mitochondrial compartments.
J Cell Biol 1988 Dec
PMID:Import pathways of precursor proteins into mitochondria: multiple receptor sites are followed by a common membrane insertion site. 297 57

Psychosine, sphingosylphosphorylcholine (52-104 microM), and other glycosphingolipids stimulate mitochondrial respiration (up to 500%) and inhibit oxidative phosphorylation to varying degrees. Above 104 microM these functions as well as uptake of Ca2+ are prevented. At 104 microM sphingosylphosphorylcholine inhibits the mitochondrial ATPase reaction in submitochondrial particles by 48%. Both sphingosylphosphorylcholine and psychosine enhance the active phosphate-dependent swelling of mitochondria. Passive swelling occurs in the presence of rotenone (when swelling does not normally occur) and under hypotonic conditions. A direct interaction of sphingosylphosphorylcholine with membranes is demonstrated by a discharge of the proton gradient across mitochondrial membranes, hemolysis of red blood cells, and binding to inner and outer mitochondrial membranes. Thus lysosphingolipids bind strongly to mitochondrial membranes and markedly alter mitochondrial function. This alteration would affect the ATP levels, thereby altering a wide range of ATP-dependent cellular functions. These results offer a partial explanation for the pathogenesis of representative lysosomal storage diseases.
Biochem Cell Biol 1988 Dec
PMID:Lysosphingolipids and mitochondrial function. II. Deleterious effects of sphingosylphosphorylcholine. 297 68

Intramitochondrial Sr2+, similar to Ca2+, inhibits oxidative phosphorylation in intact rat-liver mitochondria. Both Ca2+ and Sr2+ also inhibit the hydrolytic activity of the ATPase in submitochondrial particles. Half-maximal inhibition of ATPase activity was attained at a concentration of 2.5 mM Ca2+ or 5.0 mM Sr2+ when the concentration of Mg2+ in the medium was 1.0 mM. The inhibition of ATPase activity by both cations was strongly decreased by increasing the Mg2+ concentration in the reaction medium. In addition, kinetical data and the determination of the concentration of MgATP, the substrate of the ATPase, in the presence of different concentrations of Ca2+ or Sr2+ strongly indicate that these cations inhibit ATP hydrolysis by competing with Mg2+ for the formation of MgATP. On the basis of a good agreement between these results with submitochondrial particles and the results of titrations of oxidative phosphorylation with carboxyatractyloside or oligomycin in mitochondria loaded with Sr2+ it can be concluded that intramitochondrial Ca2+ or Sr2+ inhibits oxidative phosphorylation in intact mitochondria by decreasing the availability of adenine nucleotides to both the ADP/ATP carrier and the ATP synthase.
Biochim Biophys Acta 1986 Dec 03
PMID:Inhibition of oxidative phosphorylation by Ca2+ or Sr2+: a competition with Mg2+ for the formation of adenine nucleotide complexes. 302 7

The onset of respiration in the cyanobacteria Anacystis nidulans and Nostoc sp. strain Mac upon a shift from dark anaerobic to aerobic conditions was accompanied by rapid energization of the adenylate pool (owing to the combined action of ATP synthase and adenylate kinase) and also the guanylate, uridylate, and cytidylate pools (owing to nucleoside diphosphate and nucleoside monophosphate kinases). Rates of the various transphosphorylation reactions were comparable to the rate of oxidative phosphorylation, thus explaining, in part, low approximately P/O ratios which incorporate adenylates only. The increase of ATP, GTP, UTP, and CTP levels (nanomoles per minute per milligram [dry weight]) in oxygen-pulsed cells of A. nidulans and Nostoc species was calculated to be, on average, 2.3, 1.05, 0.8, and 0.57, respectively. Together with aerobic steady-state pool sizes of 1.35, 0.57, 0.5, and 0.4 nmol/mg (dry weight) for these nucleotides, a fairly uniform turnover of 1.3 to 1.5 min-1 was derived. All types of nucleotides, therefore, may be conceived of as being in equilibrium with each other, reflecting the energetic homeostasis or energy buffering of the (respiring) cyanobacterial cell. For the calculation of net efficiencies of oxidative phosphorylation in terms of approximately P/O ratios, this energy buffering was taken into account. Moreover, in A. nidulans an additional 30% of the energy initially conserved in ATP by oxidative phosphorylation was immediately used up by a plasma membrane-bound reversible H+-ATPase for H+ extrusion. Consequently, by allowing for energy buffering and ATPase-linked H+ extrusion, maximum P/O ratios of 2.6 to 3.3 were calculated. By contrast, in Nostoc sp. all the H+ extrusion, appeared to be linked to a plasma membrane-bound respiratory chain, thus bypassing any ATP formation and leading to P/O ratios of only 1.3 to 1.5 despite the correction for energy buffering.
J Bacteriol 1986 Dec
PMID:Oxidative phosphorylation and energy buffering in cyanobacteria. 302 99

We have labeled the nucleoside triphosphate-binding domain of Escherichia coli rho factor with the ATP affinity analog [3H]pyridoxal 5'-diphospho-5'-adenosine (PLP-AMP). PLP-AMP completely inactivates the RNA-dependent ATPase activity of rho upon incorporation of 3 mol of reagent/mol of hexameric rho protein. Although the potency of PLP-AMP is enhanced when an RNA substrate such as poly(C) is present, the stoichiometry for inhibition remains the same as in the absence of poly(C). The nucleotide substrate ATP competes very effectively for the binding site and protects against PLP-AMP inactivation. A domain of rho called N2, which comprises the distal two-thirds of the molecule (residues 152-419) and encompasses the region proposed to bind ATP, is labeled specifically in the presence of poly(C). Amino acid sequence analysis of the single [3H]PLP-AMP labeled proteolytic fragment showed Lys181 to be the site of modification, suggesting that this residue normally interacts with the gamma-phosphoryl of bound ATP. These results agree with our proposed tertiary structure for the ATP-binding domain of rho that places this lysine residue in a flexible loop above a hydrophobic nucleotide-binding pocket comprised of several parallel beta-strands, similar to adenylate kinase, F1-ATPase, and related ATP-binding proteins. Parallel studies of rho structure and function by site-directed mutagenesis and chemical modification support this interpretation.
J Biol Chem 1988 Dec 15
PMID:The ATP binding site on rho protein. Affinity labeling of Lys181 by pyridoxal 5'-diphospho-5'-adenosine. 314 17

Steady-state transcript levels of nuclear (rbcS, cab) and plastid (rbcL, psbA) encoded photosynthesis-specific genes were determined at noon and 05.00 h in different developmental stages of tomato fruits (7-35 days after anthesis). Small alterations are observed in mRNA levels for the small subunit (ssu) and large subunit (lsu) of RuBPC/Oase and the QB-binding protein of photosystem II at these two time-points, while significant steady-state transcript level fluctuations are detectable for the light harvesting complex protein. LHCP II transcripts accumulate during the day, and decline to low levels during the night. In contrast, the LHC II protein levels remain constant during the same period of development. A detailed analysis of transcript levels of the nuclear and plastid genes at 4-h intervals throughout a 38-h period demonstrates that LHCP II mRNA accumulation is highest at noon and lowest at 04.00 h. The transcripts of the ssu and lsu of RuBPC/Oase, photosystem I and II reaction center proteins, as well as the beta-subunit of the mitochondrial ATPase and the beta-subunit of tubulin, accumulate during the night and decrease to low levels in the afternoon. The transcript levels of the genes examined in this study fluctuate with certain periodicities. We suggest that gene expression in developing tomato fruits is at least partially controlled by diurnal rhythms, which are therefore also operational in other organs, besides leaves, of higher plants.
EMBO J 1987 Dec 01
PMID:Diurnal mRNA fluctuations of nuclear and plastid genes in developing tomato fruits. 342 66

Spinach chloroplast lamellae were stained with aqueous uranyl acetate immediately after glutaraldehyde-osmium fixation but before dehydration and embedding. Under these conditions, the lamellae are shown in thin sections to have 95-A x 115-A coupling factor particles on their surfaces. The particles can be seen only on the matrix side of nonopposed thylakoids, and are shown to occur on both stromal and granal lamellae, regardless of the organization of the lamellae into stacks. It is estimated that, in native, fully coupled chloroplast lamellae, there is on the average one coupling factor for every 500 chlorophyll molecules. The morphological appearance of the particles is not affected by a variety of buffers, by changes in illumination or temperature, or by alterations in the energy state of the membranes during preparation. The particles can be removed from the membranes with low concentrations of Na(2)EDTA, and the photophosphorylating activity of the membranes is concomitantly lost. Both the activity and the appearance of the particles can be restored to the membranes by rebinding EDTA-extracted coupling factors to the uncoupled membranes.
J Cell Biol 1974 Dec
PMID:The visualization of the photosynthetic coupling factor in embedded spinach chloroplasts. 414 Jan 93

Using fluorescence quenching of 9-amino-6-chloro-2- methoxyacridine induced either by ATP hydrolysis in the ATPase-ATP synthase complex or by succinate oxidation in inverted submitochondrial particles, correlation have been established between ATP hydrolysis, ATP synthesis and the generation and utilization of delta pH. The results obtained are best explained in terms of local circuits of protons.
Biochim Biophys Acta 1983 Dec 30
PMID:Correlations between ATP hydrolysis, ATP synthesis, generation and utilization of delta pH in mitochondrial ATPase-ATP synthase. 619 86

The ATP synthase complex, designated F1F0, of Escherichia coli is composed of a water-soluble portion (F1; membrane-associated ATPase, EC 3.6.1.3) with ATP-hydrolyzing activity and a membrane-integrated part (F0) with H+-translocating activity. F0 is built up from three kinds of subunits (a, b, and c). We have isolated the F0 portion directly from membranes of an E. coli strain (KY 7485) that overproduces the enzyme several fold. Subunit b was extracted from purified F0 by two methods. One method included prolonged incubation of the F0 complex in the presence of trichloroacetate (2.5 M) and the separation of subunit b and an a-c complex by gel filtration. Alternatively, subunit b was extracted by deoxycholate and separated from the a-c complex by hydrophobic-interaction chromatography. Integrated into liposomes, the a-c complex exhibited neither H+ uptake nor binding of F1. However, a functional F0 complex was reconstituted by adding stoichiometric amounts of subunit b to the a-c complex.
Proc Natl Acad Sci U S A 1984 Dec
PMID:Subunit b of the membrane moiety (F0) of ATP synthase (F1F0) from Escherichia coli is indispensable for H+ translocation and binding of the water-soluble F1 moiety. 620 11


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