Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Total ATPase levels were determined in homogenate fractions of baker's yeast, Saccharomyces cerevisiae K and Rhodotorula glutinis. The maximum ATPase activities in 8000 X g supernatant of the three yeast strains were 6.0, 1.9, and 2.2 mmol Pih-1 (gDS)-1, respectively; the activities in the sediment were somewhat higher. Exponential cells of S. cerevisiae K and R. glutinis exhibited higher ATPase levels than did the stationary cells. 2. The total ATPase activity in both yeast species showed a maximum at ph 6.8 a minimum at pH 7.2, and another broader masimum around pH 8.0. 3. No significant NaK-ATPase activity was detected in baker's yeast, in either the exponential or the stationary cells of R. glutinis, and in exponential S. cerevisiae K cells in the pH range of 6.0-9.3. 4. Stationary cells of S. cerevisiae K exhibited, at pH 7.0-8.5, A Na,K-ATPase activity attaining 9% of total ATPase level. 5.3 X 10(-3) M phenylmethyl sulphonyl fluoride had no effect on the total ATPase level in S. cerevisiae and inhibited the activity in R. glutinis by 25%; it did not bring forth any Na,K-ATPase activity apart from that found in its absence. 6. 1.5 M urea lowered the ATPase activity in R. glutinis by 68% but had no effect on S. cerevisiae cells. 10(-5) M dicyclohexylcarbodiimide suppressed the ATPase activity in S. cerevisiae and R. glutinis by 74 and 79%, respectively. Neither agent revealed and additional Na,K-ATPase activity. 7. The comparison of Na,K-ATPase activities with data on K+ fluxes across the yeast plasma membrane suggested that even with the lower flux values the Na,K-ATPase, even if present, would account for a mere 40% of transported ions. The results imply that the active ion transport in yeasts is energized by mechanisms other than the Na,K-ATPase.
Mol Cell Biochem 1976 Aug 30
PMID:Some properties of the adenosine triphosphatase systems of two yeast species, Saccharomyces cerevisiae and Rhodotorula glutinis. 0 2

The effects of acid on fragmented sarcoplasmic reticulum from rabbit white skeletal muscle have been studied. Brief exposure of sarcoplasmic reticulum membranes to pH values in the range 5.5 to 6.0 at 37 degrees caused rapid inactivation of calcium accumulation measured at 25 degrees in the presence of oxalate (calcium uptake) while (Ca2+, Mg2+)-ATPase (EC 3.6.1.3) activity was enhanced by 75%. ATPase activity, measured at 37 degrees in the absence of oxalate and in the calcium steady state, was unaltered when calcium uptake was inactivated. Calcium efflux from sarcoplasmic reticulum vesicles, previously loaded passibely with 45CaCl2, was only slightly increased when calcium uptake was abolished. At still lower pH values, 5.0 to 5.5, (Ca2+, Mg2+)-ATPase was inactivated while Mg2+ ATPase was more acid-resistant. Acid inactivation of calcium uptake followed simple first order kinetics for at least 80% of the time course. The rate constant, k, increased from 0.043 min-1 to 1.63 min-1 between pH 6.50 and pH 5.35. At pH 4.65, Ea, the energy of activation, was 31 kcal mol-1 between 24 degrees and 43 degrees. Inactivation, once initiated, was irreversible. Aged suspensions of sarcoplasmic reticulum were more sensitive to acid inactivation. Ethylene glycol bis(beta-aminoethyl ether)N,N'-tetraacetic acid enhanced inactivation, and calcium specifically protected against inactivation with half-maximal effect at 1 to 2 mM. The sulfhydryl reagent, dithiothreitol (1 mM), caused significantly increased rates of inactivation. Calcium binding was studied by dual wavelength spectrophotometry and stopped flow analysis. Acid inactivation distinguished two ATP-induced binding sites, previously described (Entman, M. L., Snow, T. R., Freed, D., and Schwartz, A. (1973) J. Biol. Chem. 248, 7762-7772) as a superficial Mg2+-independent Site A which binds and releases calcium rapidly and a deeper Mg2+-dependent Site B which binds and releases calcium more slowly. Rates of binding to both sites were decreased by acid inactivation. Binding of calcium to Site A increased, however, from 4.6 to 6.4 nmol mg of protein-1 whereas that to Site B decreased from 17.0 to 6.9 nmol mg of protein-1. Passive binding of calcium to sites of medium affinity (K = 7 X 10(4) M-1) was unaffected by acid inactivation of calcium uptake. Temperature dependence of (Ca2+, Mg2+)-ATPase was unchanged in the range 9-34 degrees. Above 34 degrees, the higher activation energy process (Ealpha = 33.7 kcal mol-1) observed in control sarcoplasmic reticulum and thought to arise from a conformational change in the ATPase (Inesi, G., Millman, M., and Eletr, S. (1973) J. Mol. Biol. 81, 483-504) was diminished by acid inactivation (Ealpha = 8.2 kcal mol-1) in a manner suggesting that it is related to active calcium transport. The ATP in equilibrium 32Pi exchange reaction was diminished by acid, but 25% of the activity remained when calcium uptake was completely abolished...
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PMID:Proton inactivation of Ca2+ transport by sarcoplasmic reticulum. 1 42

1. Plasma membrane preparations have been isolated from spheroplasts of Saccharomyces cerevisiae, strain R XII, via lysis and subsequent differential centrifugation. These preparations are almost devoid of mitochondrial contamination. 2. The plasma membrane ATPase is fairly stable when refrigerated, but loses activity at 8 degrees C and above. Below pH 5.6 the ATPase is irreversibly inactivated. The enzyme also splits GTP and ITP, although to a lesser extent. 3. Mg2+-ions are essential as part of the reactive substrate, MgATP, and furthermore they activate the ATPase. Optimal conditions depend on substrate concentration. When the concentration of free Mg2+ ions exceeds about 0.1 mM, competitive inhibition occurs. 4. In the range of pH 5.6-9.2 two functional groups dissociate. One, with pKb = 8.1 +/- 0.1 participated in substrate binding and another one with pKb' = 8.1 +/- 0.1 is involved in substrate splitting. 5. The experiments with group-specific inhibitors suggest that an alpha-amino group and a sulfhydryl residue are involved in substrate binding and conversion. Furthermore, imidazole, tryptophan and carboxyl residues may be important for the catalytic process.
Mol Cell Biochem 1978 Nov 30
PMID:Kinetic characterization of plasma membrane ATPase from Saccharomyces cerevisiae. 3 25

1. Intracellular electrolytes, and erythrocyte membrane adenosine triphosphatase (ATPase) activity, was studied in twenty patients after renal transplantation. 2. The mean ouabain-sensitive ATPase activity in the erythrocyte membranes of the transplant patients was 122 nmol of inorganic phosphorus (Pi) h-1 mg of tissue-1 (SEM 14), compared with 62 nmol of Pi h-1 mg of tissue-1 (SEM 8) in a group of paired, healthy controls. 3. The increase in ouabain-sensitive ATPase was most marked in the 4 months after transplantation. However, a significant increase in ouabain-sensitive ATPase persisted for more than 8 months after transplantation. 4. This increase in ouabain-sensitive ATPase was associated with a decrease in intracellular sodium in the erythrocytes of the transplant patients.
Clin Sci Mol Med 1975 Mar
PMID:Changes in erythrocyte membrane ouabain-sensitive adenosine triphosphatase after renal transplantation. 12 85

1. The function of mitochondria, sarcotubular membranes (heavy microsomes), sarcolemma and myofibrils from the hind-leg skeletal muscle of about 60- and 150-day-old normal and myopathic (UM-X7.1) hamsters was examined. 2. The mitochondrial calcium uptake as well as mitochondrial phosphorylation and respiratory rates were lower in 60-day-old myopathic skeletal muscle, unlike 150-day-old myopathic animals, when pyruvate-malate and glutamate-malate were used as substrates. However, mitochondria from 150-day-old myopathic animals showed depressed glutamate-dependent respiratory and phosphorylation rates and succinate-supported initial rate of calcium uptake. 3. The microsomal calcium-uptake, but not calcium-binding, and Ca2+-stimulated adenosine triphosphatase (ATPase) activity of the 150-day-old myopathic skeletal muscle were lower than the control values. Although microsomal calcium-binding, calcium-uptake and ATPase activities of the 60-day-old myopathic muscle were not depressed significantly, the initial rate of calcium uptake was less than the control. 4. The sarcolemmal Ca2+-ATPase, but not Mg2+-ATPase or Na+ +K+-ATPase, activity was higher in 60-day-old myopathic muscle whereas the activities of all these enzymes from 150-day-old myopathic animals were higher than the control. On the other hand, the Na+ +K+-ATPase activities from 60- and 150-day-old myopathic animals were inhibited by ouabain to a lesser extent in comparison with the respective control values. 5. The myofibrillar Ca2+-ATPase and Mg2+-ATPase activities as well as inhibition of Mg2+-ATPase due to Na+ and K+ in myopathic muscle were no different from the control values. 6. The results reported here give further support to the view that different membrane systems of the dystrophic muscle are defective.
Clin Sci Mol Med 1975 Oct
PMID:Defective membrane systems in dystrophic skeletal muscle of the UM-X7.1 strain of genetically myopathic hamster. 12 86

Basal and trypsin-stimulated adenosine triphosphatase activities of Escherichia coli K 12 have been characterized at pH 7.5 in the membrane-bound state and in a soluble form of the enzyme. The saturation curve for Mg2+/ATP = 1/2 was hyperbolic with the membrane-bound enzyme and sigmoidal with the soluble enzyme. Trypsin did not modify the shape of the curves. The kinetic parameters were for the membrane-bound ATPase: apparent Km = 2.5 mM, Vmax (minus trypsin) = 1.6 mumol-min-1-mg protein-1, Vmax (plus trypsin) = 2.44 mumol-min-1-mg protein-1; for the soluble ATPase: [S0.5] = 1.2 mM, Vmax (-trypsin) = 4 mumol-min-1-mg protein-1; Vmax (+ trypsin) = 6.6 mumol-min-1-mg protein-1. Hill plot analysis showed a single slope for the membrane-bound ATPase (n = 0.92) but two slopes were obtained for the soluble enzyme (n = 0.98 and 1.87). It may suggest the existence of an initial positive cooperativity at low substrate concentrations followed by a lack of cooperativity at high ATP concentrations. Excess of free ATP and Mg2+ inhibited the ATPase but excess of Mg/ATP (1/2) did not. Saturation for ATP at constant Mg2+ concentration (4 mM) showed two sites (groups) with different Kms: at low ATP the values were 0.38 and 1.4 mM for the membrane-bound and soluble enzyme; at high ATP concentrations they were 17 and 20 mM, respectively. Mg2+ saturation at constant ATP (8 mM) revealed michealian kinetics for the membrane-bound ATPase and sigmoid one for the protein in soluble state. When the ATPase was assayed in presence of trypsin we obtained higher Km values for Mg2+. These results might suggest that trypsin stimulates E. coli ATPase by acting on some site(s) involved in Mg2+ binding. Adenosine diphosphate and inorganic phosphate (Pi) act as competitive inhibitors of Escherichia coli ATPase. The Ki values for Pi were 1.6 +/- 0.1 mM for the membrane-bound ATPase and 1.3 +/- 0.1 mM for the enzyme in soluble form, the Ki values for ADP being 1.7 mM and 0.75 mM for the membrane-bound and soluble ATPase, respectively. Hill plots of the activity of the soluble enzyme in presence of ADP showed that ADP decreased the interaction coefficient at ATP concentrations below its Km value. Trypsin did not modify the mechanism of inhibition or the inhibition constants. Dicyclohexylcarbodiimide (0.4 mM) inhibited the membrane-bound enzyme by 60-70% but concentrations 100 times higher did not affect the residual activity nor the soluble ATPase. This inhibition was independent of trypsin. Sodium azide (20 muM) inhibited both states of E. coli ATPase by 50%. Concentrations 25-fold higher were required for complete inhibition. Ouabain, atebrin and oligomycin did not affect the bacterial ATPase.
Mol Cell Biochem 1975 Nov 14
PMID:Membrane bound and soluble adenosine triphosphatase of Escherichia coli K 12. Kinetic properties of the basal and trypsin-stimulated activities. 12 30

The isolation and characterisation of a mutant affecting the assembly of mitochondrial ATPase is reported. The mutation confers resistance to oligomycin and venturicidin and sensitivity of growth on nonfermentable substrates to low temperature (19degrees). Genetic analysis indicates that the phenotype is due to a single mutation located on the mitochondrial DNA which is probably allelic with the independently isolated oligomycin resistance mutation [oli1-r]. Growth of the mutant at the non-restrictive temperature (28degrees) yields mitochondria in which the ATPase appears more sensitive to oligomycin than that of the sensitive parental strain. However, when the enzyme is isolated free from the influence of the membrane strong resistance to oligomycin is evident. These data suggest that the component responsible for the oligomycin resistance of the ATPase is part of or subject to interaction with the mitochondrial inner membrane. Measurements of the ATPase content of mitochondria indicate that ATPase production is impaired during growth at 19degreesC. In addition, studies of the maximum inhibition of mitochondrial ATPase activity by high concentrations of oligomycin suggest a selective lesion in ATPase assembly at low temperature. The nett result is that during growth at 19degrees only about 10% of the normal level of ATPase is produced of which less than half is membrane integrated and thus capable of oxidative energy production. We propose that the mutation affects a mitochondrially synthesised membrane sector peptide of the ATPase which defines the interaction of F1ATPase with specific environments on the mitochondrial inner membrane.
Mol Gen Genet 1975 Nov 03
PMID:Biogenesis of mitochondria 36, The genetic and biochemical analysis of a mitochondrially determined cold sensitive oligomycin resistant mutant of Saccharomyces cerevisiae with affected mitochondrial ATPase assembly. 12 72

Two new forms of the plasma membrane ATP-ase of Micrococcus lysodeikticus NCTC 2665 were isolated from a sub-strain of the microorganism by polyacrylamide gel electrophoresis. One of them had a mol.wt of 368,000 and a very low specific activity (0.80 mumol.min-1.mg protein-1) that could not be stimulated by trypsin. This form has been called B1 (strain B, inactive). If the elctrophoresis was carried out in the presence of reducing agents (i.e., dithiothreitol) and the pH of the effluent maintained at a value of 8.5 another form of the enzyme was obtained. This had a mol.wt of 385,000 and a specific activity of 2.5-5.0 mumol.min-1.mg protein-1 that could be stimulated by trypsin to 5-10 mumol.min-1.mg protein-1. This preparation of the ATPase has been called from BA (strain B, enzyme active). The subunit composition of both forms has been studied by sodium dodecyl sulphate and urea gel electrophoresis and compared to that of the enzyme previously purified from the original strain (form A). The three forms of the enzyme had similar beta and delta subunits, with mol.wt of about 50,000 and 30,000 dalton, respectively. They also had in common the component(s) of relative mobility 1.0, whose status as true subunit(s) of the enzyme remains yet to be established. However, subunit alpha, that had a mol.wt of about a 52,500 in form A (ANDREU et al. Eur. J. Biochem. (1973) 37, 505-515), had a mol.wt similar to beta in form B1 and about 60,000 in form BA. Furthermore BA usually showed two types of this subunit (alpha' and alpha") and an additional peptide chain E) with a mol.wt of about 25,000 dalton. This latter subunit seemed to account for the stimulation by trypsin of form BA. Forms BA could be converted to B1 by storage and freezing and thawing. Conventional protease activity could not be detected in any of the purified ATPase forms and addition of protease inhibitors to form BA failed to prevent its conversion to form B1. The low activity form (B1) was more stable than the active forms of the enzyme and also differeed in its circular dichroism. These results show that M. lysodeikticus ATPase can be isolated in several forms. Although these variations may be artifacts caused by the purification procedures, they provide model systems for understanding the structural and functional relationships of the enzyme and for drawing some speculations about its function in vivo.
Mol Cell Biochem 1976 Feb 16
PMID:Membrane adenosine triphosphatase of Micrococcus lysodeikticus. ISolation of two forms of the enzyme complex and correlation between ezymatic stability, latency and activity. 13 May 38

1. The effect of treating rats with digoxin and thyroxine for 45 days has been studied. 2. Animals fed with digoxin gained significantly more weight than the control animals. 3. Treatment with digoxin, thyroxine or both produced a similar significant increase in the amount of Na+ + K+ -dependent adenosine triphosphatase in liver without an additive effect. 4. It is suggested that digoxin resistance in thyrotoxicosis may be related to this similarity in action.
Clin Sci Mol Med 1976 May
PMID:Rat hepatic sodium plus potassium ion-dependent adenosine triphosphatase after treatment with digoxin and thyroxine. 13 31

Immobilization of myosin, actin, actomyosin and subfragment S1 on kapron fibre was achieved with the help of glutaric aldehyde. The ATPase activity of myosin and its ability to interact with actin is preserved; while the ATPase activity of S1 subfragment decreases considerably. The immobilization on kapron fibre changes the pH-dependance of ATPase activity of myosin and that of subfragment S1, shifting the maximum to low pH zone (pH 5.5), and increases the thermostability of the enzyme. The ions of Ca++ in all cases act as an activating agent on ATPase while the ions of Mg++ either do not affect myosin and subfragment S1 at all, or increase the activity in the case of the immobilized of actomyosin but to a lesser degree than the ions of Ca++. The immobilized actin preserves its ability to form actomyosin complex.
Mol Biol (Mosk)
PMID:[Chemical suturing of myosin and actin to capron fiber]. 13 56


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