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Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have compared the adenosine triphosphatase (ATPase) activity of mitochondria prepared from wild-type Neurospora crassa and from poky, a maternally inherited mutant known to possess defective mitochondrial ribosomes and reduced amounts of cytochromes aa3 and b. poky contains two distinct forms of mitochondrial ATPase. The first is normal in its Km for ATP, specificity for nucleotides and divalent cations, pH optimum, cold stability, and sensitivity to inhibitors (oligomycin, N,N-dicyclohexyl carbodiimide, and adenylyl imidodiphosphate). The fact that membrane-bound, cold-stable, oligomycin-sensitive ATPase activity is present in poky (with an activity of 1.93 +/- 0.03 mumol/min-mg of protein compared with 1.33 +/- 0.07 mumol/min-mg of protein in the wild-type strain) and also in chloramphenicol-grown wild-type cells suggests that products of mitochondrial protein synthesis play only a limited role in the attachment of the mitochondrial ATPase to the membrane in Neurospora. poky also contains a second form of mitochondrial ATPase, which has an activity of 1.5 +/- 0.2 mumol/min-mg of protein, is oligomycin sensitive but cold labile, and presumably is attached less firmly to the mitochondrial membrane. The two forms, added together, represent a substantial overproduction of mitochondrial ATPase by poky.
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PMID:Mitochondrial adenosine triphosphatase of wild-type and poky Neurospora crassa. 2 38

The effects of fixation with various concentrations of glutaraldehyde or formaldehyde, acetone or ethanol, and freeze-drying on 5 phosphatases of Eimeria tenella and chick kidney cell cultures were demonstrated in situ. Gultaraldehyde inactivated the phosphatases more than did the formaldehyde, but the effect of the combination of the 2 (Karnovsky's fixative) was greater than that of either glutaraldehyde or formaldehyde alone. The higher the concentration of aldehyde and the longer the duration of exposure, the greater the inactivation. The order of sensitivity to aldehyde fixation of the enzymes tested was glucose-6-phosphatase greater than thiamine pyrophosphatase greater than 5'-nucleotidase greater than adenosine triphosphatase greater than acid phosphatase. Cytologic detail was preserved more efficiently with glutaraldehyde than with formaldehyde. Optimal preservation of enzyme activity for cytochemistry was with 2% glutaraldehyde for 30 min or 2% formaldehyde for 1 hr for G-6-Pase, TPPase, and 5'-nucleotidase, and with 2% glutaraldehyde or 2% formaldehyde for 2 hr with ATPase and AcPase. Quenching with subsequent fixation in cold acetone or ethanol resulted in complete inactivation of G-6-Pase, TPPase, and 5'-nucleotidase; although cells fixed in this manner yielded large amounts of reaction product for ATPase and AcPase, the distribution was diffuse, and some of it appeared to be artifactual. Quenching with subsequent freeze-drying was unsatisfactory because nearly all of the cell layers rolled off the cover glasses.
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PMID:Effect of fixation on demonstration of phosphatases of Eimeria tenella grown in chick kidney cell cultures. 6 Dec 71

Vasodilator responses to acute intra-arterial infusions of K+ are attenuated in dogs with chronic one-kidney perinephritic hypertension in rats with chronic two-kidney Goldblatt hypertension, and in men with essential hypertension. There is evidence that K+ evokes vasodilation by stimulating vascular smooth muscle membrane Na+-K+-activated adenosine triphosphatase, thereby increasing activity of the cellular Na+-K+ electrogenic pump. We therefore proposed that there may be an underlying decrease in the operation of this pump in vascular smooth muscle of hypertensives. The operation of the cellular Na+-K+ pump may be estimated by measurement of rubidium uptake. Thus, so further investigate our hypothesis, we measured 86Rb uptake in small mesenteric arteries and splanchnic veins from 12 dogs with chronic uncomplicated one-kidney perinephritic hypertension and from 12 normotensive control dogs. Vessels were excised under thiamylal anesthesia and incubated in cold medium (plasma or Krebs-Henseleit solution) for sodium loading and then the velocity of 86Rb uptake was estimated in the absence of or in the presence of ouabain, a specific inhibitor of the Na+-K+ pump. In neither arteries nor veins was there evidence for differences between hypertensives and normotensives in the ouabain-insensitive uptake of 86Rb. In contrast, the ouabain-sensitive 86Rb uptake was depressed by 42% in arteries (P less than 0.05) and by 49% in veins (P less than 0.01) from hypertensive dogs, if incubated in the dog's own plasma. These results indicate that the activity of a ouabain-sensitive Na+-K+ pump may be depressed in vascular tissue from dogs with chronic one-kidney perinephritic hypertension. Because the Na+-K+ pump in vascular smooth muscle is probably electrogenic, such an abnormality, by partially depolarizing the muscle cell membrane, would help to account for the elevated vascular resistance found in these dogs.
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PMID:Depressed function of a ouabain-sensitive sodium-potassium pump in blood vessels from renal hypertensive dogs. 13 55

A mutant Escherichia coli, selected for resistance to the antibiotic neomycin, was unable to utilize nonfermentable carbon sources for growth. Two strains were selected from this mutant on the basis of their ability to grow utilizing succinate as a carbon source. All three strains had approximately equal amounts of the Mg2+-adenosine triphosphatase (ATPase) (EC 3.6.1.3) protein, but the activity of the enzyme differed in each strain. The Mg2+-ATPase from each of the three strains lost activity upon solubilization and appeared to undergo rapid dissociation once solubilized. This dissociation is similar to that described for the wild type after cold exposure.
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PMID:Properties of Escherichia coli mutants with alterations in Mg2+-adenosine triphosphatase. 13 56

1. Soluble ATPase (adenosine triphosphatase) activity is released when rat liver submitochondrial particles are shaken with chloroform, provided that ATP or glycerol is present in the suspending medium. The extraction is very rapid and appears to be complete. 2. The ATPase of the chloroform extract is about 50% pure and can be readily purified to a specific activity of 60-70mumol/min per mg of protein by (NH(4))(2)SO(4) fractionation and column chromatography on Sephadex G-200. 3. The particulate and soluble ATPases have many similar properties, including their K(m) values for ATP, activation by various metal ions, hydrolytic activity with other nucleotides and stimulation by bicarbonate ions. 4. Unlike the particulate enzyme, the soluble enzyme is cold-labile and insensitive to oligomycin. 5. The molecular weight indicated by the mobility of the soluble ATPase on Sepharose 6B is 360000. 6. The soluble ATPase combines very readily with liver submitochondrial particles depleted of ATPase by salt extraction, and oligomycin-sensitivity is restored. Very little recombination of the enzyme occurs with chloroform-extracted particles. 7. The soluble enzyme contains orcinol-reactive material, suggesting that it may be a glycoprotein. The carbohydrate content was estimated to be 1-2% by weight. 8. It is concluded that the liver ATPase obtained by the chloroform extraction method of Beechey, Hubbard, Linnett, Mitchell & Munn [(1975) Biochem. J.148, 533-537] is similar to other preparations described previously and that this method is superior in simplicity and speed.
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PMID:Purification and properties of the adenosine triphosphatase released from the liver mitochondrial membrane by chloroform. 15 21

The histochemical activities of myofibrillar adenosine triphosphatase (ATPase), succinic dehydrogenase (SDH) and alpha glycerophosphate dehydrogenase (alpha-GPD) were studied in intrafusal muscle fibres of rat fast and slow muscles. The ATPase reaction was carried out after the three standard acid preincubations. The cold K2-EDTA preincubated ATPase reaction product was similar to that seen following the regular or alkali-preincubated ATPase reaction, except that the intermediate bag fibres exhibited much higher activity after cold K2-EDTA preincubation. Following either acetic acid solution or cold and room temperature K2-EDTA-preincubation, followed by the ATPase reaction, chain fibres of the fast muscles vastus lateralis and extensor digitorum longus exhibited a very low amount of reaction product as compared with those of the slow soleus. Veronal acetate and K2-EDTA preincubations (and equally preincubation in acetic acid solution) resulted in acid stable ATPase activity along the entire length of the typical bag fibres but only in the polar regions of the intermediate bag fibres. On the basis of differing alpha-GPD reaction, two sub populations of nuclear chain fibres were discovered in one spindle. It is a matter of conjecture, to what extent the histochemical differences of intrafusal fibres from fast and slow muscles reflects functional distinctions in the response to stretch of muscle spindles from fast and slow muscles.
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PMID:A histoenzymatic study of rat intrafusal muscle fibres. 15 74

Small cultures of human amniotic cells were preincubated for 24 h. Human prolactin was then added to the medium. After a further short period of incubation the tubes were chilled, the medium removed and the cells rinsed with saline. The tubes then received cold Tris-sucrose and were frozen, to disrupt the cells. After thawing, adenosine triphosphatase (ATPase) and p-nitrophenyl phosphatase (PNPase) were measured. Buffer was added containing either ATP or PNP and the tubes were incubated for 30 min. Inorganic phosphate released from ATP and p-nitrophenol was measured spectrophotometrically. Prolactin stimulated both enzyme activities. The ATPase log dose-response curve was linear between approximately 12.5 and 200 mIU/l. It was inhibited by ouabain. Isobutyl-1-methylxanthine inhibited the ATPase but not the alkaline phosphatase activity. One of these human amniotic cell enzymes may provide the basis for a sensitive bioassay for human prolactin.
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PMID:Enzyme activation of human prolactin: a potential basis for a bioassay. 247 90

The effects of pressure and temperature on an integral membrane protein, Na+/K+-adenosine triphosphatase (Na+/K+-ATPase), were studied in fish gill membrane preparations from shallow- and deep-living marine teleosts. The inhibition by pressure of maximal velocity of the enzyme is nonlinear, increasing at higher pressures. Na+/K+-ATPases from deep-sea fish were less inhibited by pressure than those of shallow-living species. Habitat temperature also affected the pressure response of the enzyme. As a function of physiological pressure and temperature, the order of increasing pressure-sensitivity was cold, deep-sea less than warm, deep-sea (hydrothermal vents) less than polar = shallow and mid-depth, cold less than shallow, warm. Activation volumes in all species were conserved at 30-60 ml mol-1 at physiological pressures, which may reflect a similar membrane physical state at the actual pressure the animal experiences. Arrhenius plots [In(Na+/K+-ATPase activity) vs 1/T] were steeper for warm-water and shallow-living species than for deep-sea species. The depth at which adaptation was first observed was about 2000 m (approximately equal to 200 atm: 1 atm = 101.3 kPa). The data are consistent with a model of increased membrane fluidity resulting in reduced pressure-sensitivity of Na+/K+-ATPase from deep-sea species.
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PMID:Pressure adaptation of Na+/K+-ATPase in gills of marine teleosts. 254 29

The nasal passages are anatomically complex, and while there have been a number of descriptions of nasal structure in many species, there is very little information available on the distribution of enzymes in the nasal mucosa. In rodents, this delicate mucosa is the first site within the respiratory tract to be exposed during inhalation toxicology studies designed to assess human risks from such exposures. However, the nasal mucosa presents problems for histologic preparation because it is encased in brittle bones. Because of recent interest in the nose as a target site, and findings from biochemical studies which indicate that the nose is very active metabolically, studies were carried out to determine the value of cold glycol methacrylate (GMA) processing for localization of nasal enzymes. For these studies, liver and kidney were used as positive controls. Published histochemical procedures for acid and alkaline phosphatase, adenosine triphosphatase, glucose-6-phosphatase, gamma-glutamyl transpeptidase, and naphthyl butyrate esterase were applied, with modifications, to undecalcified nasal passages of Fisher-344 rats. Frozen sections exhibited excellent enzyme preservation but very poor morphology, while GMA gave good enzyme preservation and excellent morphology. For GMA, acetone fixation generally resulted in the best preservation of enzyme activity. It was concluded that cold GMA processing provides a useful approach to studies of nasal enzyme distribution and that this technique of value for inhalation toxicology studies. Details of enzyme distribution in the squamous, respiratory, and olfactory epithelia, associated glands, and other structures of the nose of the rat are described and discussed.
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PMID:Enzyme histochemistry of the rat nasal mucosa embedded in cold glycol methacrylate. 288 3

The catalytic properties of cuckoo-pint (Arum maculatum) mitochondrial adenosine triphosphatase have been analysed. The pH profile, effect of inhibitors, cold-stability and substrate specificity are characteristic of mitochondrial adenosine triphosphatases, although a high guanosine triphosphatase activity does appear to be restricted to plant mitochondrial adenosine triphosphatases. The kinetic properties of nucleoside 5'-triphosphate hydrolysis by membrane-bound and soluble enzymes have been studied by means of double-reciprocal plots. These plots were linear in the absence of an activating anion, which may indicate that the catalytic and/or regulatory mechanism of Arum maculatum adenosine triphosphatase is different from that of other enzyme preparations. It is suggested that the differences in subunit composition of plant and mammalian adenosine triphosphatases reported previously [Dunn, Slabas & Moore (1985) Biochem. J. 225, 821-824] are structurally, rather than functionally, significant.
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PMID:Characterization of cuckoo-pint (Arum maculatum) mitochondrial adenosine triphosphatases. 293 28


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