Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The physical, chemical and enzymic properties of subfragment 1 prepared from myosin of rabbit skeletal muscle by using two different concentrations of insoluble papain were compared. 2. Subfragment 1 prepared by using a myosin/papain ratio of 2000: 1 (by wt.) migrated on electrophoresis in non-dissociating conditions as a single enzymically active band. When prepared with a myosin/papain ratio of 200: 1 the preparation consisted of two enzymically active components of slightly different electrophoretic mobility. 3. The two types of preparation were obtained in similar yield and possessed similar specific adenosine triphosphatase activities when determined in the presence of Ca(2+). 4. Gel electrophoresis in the presence of 8m-urea showed that both preparations contained three light components. The component of molecular weight 15500 was apparently identical with one of the light-chain components of myosin (Ml(1)). The other two light-chain components of subfragment 1 were not identical with any of the light-chain components of myosin. 5. The heavy-chain fraction of subfragment 1 prepared by using low concentrations of papain dissociated into components with molecular weights of 87000, 69000 and 26000 on electrophoresis in sodium dodecyl sulphate. The heavy-chain fraction of subfragment 1 prepared by using higher concentrations of papain contained components with molecular weights of 69000 and 53000 and relatively increased amounts of the component of molecular weight 26000. 6. The isolated 26000 dalton component had an amino acid composition similar to that of the heavy-chain fraction of subfragment 1 and contained 3-methylhistidine and mono-and tri-N(epsilon)-methyl-lysine. It was homogeneous on electrophoresis in the presence of sodium dodecyl sulphate but gave two bands on electrophoresis in 8m-urea.
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PMID:Studies on the heterogeneity of subfragment-1 preparations. Isolation of a new proteolytic fragment of the heavy chain of myosin. 426 20

1. Free thiol groups were shown to be essential for tropomyosin to effect maximum inhibition of the Ca(2+)-stimulated ATPase (adenosine triphosphatase) of desensitized actomyosin but not for its activity in the regulatory-protein system. 2. The activity of tropomyosin on the Mg(2+)-stimulated ATPase in the regulatory-protein system was more susceptible to enzymic digestion and thermal denaturation than its effect on the Ca(2+)-stimulated ATPase of actomyosin. 3. Rabbit skeletal tropomyosin migrated as two distinct electrophoretic components in the presence of sodium dodecyl sulphate and urea and as four components on isoelectric focusing in urea. 4. The two main subunits present in rabbit skeletal tropomyosin, which have been named the alpha- and beta-chains, were separated by chromatography on CM-cellulose in urea at pH4.0. They were shown to be virtually identical in amino acid composition, except for their cysteine contents. The alpha(2) and beta(2) forms of tropomyosin possessed all the biological activities characteristic of normal tropomyosin preparations. 5. In skeletal muscle the alpha and beta components of tropomyosin were present in the proportion of 4:1. Somewhat lower ratios were obtained in skeletal muscle of sheep, pig and cow. 6. Tropomyosin isolated from cardiac muscle and Pecten maximus adductor muscle migrated as one band only. These tropomyosins possessed similar biological activities to those isolated from skeletal muscle.
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PMID:The subunits and biological activity of polymorphic forms of tropomyosin. 427 Jun 62

The platelet content of adenosine triphosphate (ATP), adenosine diphosphate (ADP), serotonin and ouabain-insensitive, magnesium-dependent adenosine triphosphatase (ATPase) was determined in patients with chronic renal failure, patients on chronic hemodialysis, and kidney transplant recipients. Platelet ATP content was normal in all. By contrast, ADP content, expressed in mumol/10(11) platelets, was significantly lower in renal failure: 1.82 +/- 0.96 compared to 2.51 +/- 0.97 in normals (p less than 0.05), but not in dialyzed or transplanted patients; 2.27 +/- 0.96 and 1.87 +/- 0.87, respectively. The mean content of serotonin was also significantly lower in renal failure patients: 0.52 microgram/10(9) platelets as compared to 0.90 microgram/10(9) platelets in normals (p less than 0.05) but was not significantly different in dialyzed and transplanted patients. ATPase was significantly lower in renal failure: 3.13 +/- 1.2 mumol Pi/10(9) platelets in whole suspension and 0.71 +/- 0.22 Pi/mg protein/h in membrane preparation compared to 4.74 +/- 1.1 and 1.18 +/- 0.19, respectively, in normals, and was significantly lower in dialyzed and transplanted patients. Experimental azotemia (BUN 65-86 mg/100 ml), induced by the oral ingestion of urea 2-3 g/kg body weight over 24 h, failed to induce any of these abnormalities. The abnormality in platelet ADP and serotonin content in renal failure paralleled the functional platelet defects which characterize these patients and were reversible following dialysis and transplantation.
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PMID:Biochemical abnormalities of platelets in renal failure. Evidence for decreased platelet serotonin, adenosine diphosphate and Mg-dependent adenosine triphosphatase. 621 10

The presence of an altered form of the heavy chain component of myosin subfragment-1 (S-1) in avian dystrophic pectoral muscle was confirmed by Triton-urea-acetic acid polyacrylamide gel electrophoresis. The potential functional significance of this altered form of S-1 was evaluated by measuring the ATPase activity of the unregulated acto-S-1 complex using all possible pairwise combinations of actin and S-1 from normal (N) and dystrophic (D) muscle. (NN, DD, ND, DN, where the first letter designates the actin and the second letter the S-1). With conventionally purified actin and S-1, NN not equal to DD not equal to ND not equal to DN, implying both N actin not equal to D actin and N S-1 not equal to D S-1 functionally. An alternate purification scheme for actin resulted in preparations from normal and dystrophic muscles of actin Mg-polymers with the same rheology (viscosity vs shear rate) and critical concentration for polymerization. When these actins were combined with more highly purified preparations of S-1, the adenosine triphosphatase (ATPase) activity of the acto-S-1 complex did not vary with changes in the pairwise composition and responded similarly to variation of the actin or adenosine triphosphate (ATP) concentration. In experiments with actin activation of intact myosin, no differences were observed between myosin from normal vs dystrophic muscle. The different isozymes of myosin present in normal and dystrophic chicken pectoral muscles are functionally equivalent as ATPases in their interactions with unregulated actin.
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PMID:The interaction of unregulated actin and myosin in avian muscular dystrophy. 624 14

The catalytic subunit of sodium and potassium ion transport adenosine triphosphatase was isolated by sodium dodecyl sulfate-polyacrylamide electrophoresis and was subjected to isoelectric focussing on 3.5% acrylamide in 2% Triton X-100, 9 M urea, and 2% Bio-Lyte 3/10 from Bio-Rad Laboratories. At 20 degrees C this resolved 2 equal and closely spaced bands centered at pH 5.5 about 0.04 pH unit apart. The distribution of the polypeptide between the 2 bands came to a temperature-dependent equilibrium during focussing. At 15 degrees C predominantly the acidic band and at 25 degrees C predominantly the alkaline band appeared. Perhaps association of the nonionic detergent with the polypeptide resulted in its partitioning into bands corresponding to different physical states. A change of phase in a polypeptide-detergent complex might have altered its charge. To test functional homogeneity of the subunit in the native enzyme, the active center for ATP binding was covalently labeled with fluorescein isothiocyanate, an acidic ligand. Isoelectric focussing of the derivatized subunit at 20 degrees C showed displacement of all of the alkaline band to the position of the acidic band, which was fluorescent. Isoelectric focussing at 25 degrees C showed displacement of almost half of the alkaline band to the position of the acidic band, and both bands were fluorescent. The results suggest that all of the subunit accepted the fluorescent label and that derivatization slightly raised the temperature at which the polypeptide equilibrated between the 2 states. A few experiments on the calcium-dependent ATPase of sarcoplasmic reticulum indicated that it responded similarly.
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PMID:Isoelectric focussing of the catalytic subunit of (Na,K)-ATPase from pig kidney. 630 Jan 24

The inhibitory subunit (epsilon) of the F1 adenosine triphosphatase (ATPase) was purified to homogeneity from the ML 308-225 and K12 (lambda) strains of Escherichia coli. No tryptophan or cysteine was detected in the subunit from either strain. The highly active epsilon from both strains was found to be a globular protein with a Stokes' radius of 18--19 A. Circular dichroism spectra suggested an alpha-helix content of approximately 40%. The molecular weight of epsilon was approximately 15000--16000 by sedimentation equilibrium centrifugation in the presence and absence of guanidinium hydrochloride, molecular sieve chromatography, and gel electrophoresis in the presence of sodium dodecyl sulfate and 8 M urea. The s20,w of epsilon was approximately 1.6 s-1. Inhibition of the purified F1 ATPase by epsilon displayed noncompetitive kinetics with a Ki of approximately 10 nM. The inhibition of the ATPase was rapidly reversed by diluting the enzyme--epsilon mixture. [125I]epsilon which was incorporated into ECF1 was readily displaced by unlabeled epsilon. epsilon had no significant effect on the ATPase activity of "native" or reconstituted everted membrane vesicles under a variety of assay conditions. Combining the epsilon-inhibited F1 ATPase with its hydrophobic portion in everted membrane vesicles reconstituted the reversible proton-translocating ATPase and restored nearly full ATPase activity. These results suggest that epsilon inhibits the enzyme only when the F1 ATPase becomes detached from its hydrophobic subunits.
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PMID:Characterization of the inhibitory (epsilon) subunit of the proton-translocating adenosine triphosphatase from Escherichia coli. 644 14

Myosin was isolated from the free right and left ventricular wall of normal adult human myocardium and purified until actin contamination was considered negligible as judged by sodium dodecyl sulphate polyacrylamide gel electrophoresis and adenosine triphosphatase assay in the presence of magnesium chloride. Ca2+ and K+ ethylenediaminetetra-acetic acid activated adenosine triphosphatase activities were determined in the presence of 3 mmol.litre-1 adenosine triphosphate. Myosin light chain subunits, VLC-1 and VLC-2, were analysed by polyacrylamide gel electrophoresis using: (i) sodium dodecyl sulphate at pH 7.0; (ii) 6 mol.litre-1 urea at pH 8.5; and (iii) isoelectric focusing in 9.2 mol.litre-1 urea over the pH range 4 to 6. No inherent differences in enzymic or physiochemical properties of the myosins from the human right and left ventricle were observed. Similar results were obtained in the baboon and dog.
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PMID:Myosin adenosinetriphosphatase activity and light chain subunit composition of human right and left ventricle. 645 7

The regulatory myosin light chain (MLC) is phosphorylated in cardiac muscle by Ca2+/calmodulin-dependent MLC kinase (MLCK) and is considered to play a modulatory role in the activation of myofibrillar adenosine triphosphatase (ATPase) and the process of force generation. Since the depression in cardiac contractile function in chronic diabetes is associated with a decrease in myofibrillar ATPase activity, we investigated changes in MLC phosphorylation in diabetic heart. Rats were made diabetic by injecting streptozotocin (65 mg/kg intravenously), and the hearts were removed 8 weeks later; some 6-week diabetic animals were injected with insulin (3 U/d) for 2 weeks. Changes in the relative MLC and MLCK protein contents were measured by electrophoresis and immunoblot assay, whereas phosphorylated and unphosphorylated MLCs were separated on 10% acrylamide/urea gel and identified by Western blot. MLC and MLCK contents were decreased markedly (40% to 45%) and MLC phosphorylation was decreased significantly (30% to 45%) in the diabetic rat heart homogenate in comparison to control values. The changes in MLC and MLCK content in diabetic heart were partially reversible, whereas changes in MLC phosphorylation were normalized upon treatment with insulin. These results suggest that decreased protein contents of MLC and MLCK and phosphorylation of MLC may contribute to the depression of cardiac myofibriliar ATPase activity and heart dysfunction in diabetic cardiomyopathy.
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PMID:Myosin light-chain phosphorylation in diabetic cardiomyopathy in rats. 900 73

The aim of our work was to study the changes in activity, abundance and distribution of sodium, potassium-adenosine triphosphatase (Na+,K+-ATPase) in membranes of cortical tubular cells in an in vivo model of ischemic injury without reperfusion. Na+,K+-ATPase, alkaline phosphatase (AP) activities and their distribution in membranes isolated from renal cortex using a Percoll gradient were studied after different ischemic periods. Na+,K+-ATPase alpha-subunit protein abundance was analysed by Western-blot. Plasma urea and cortical adenosine 5' triphosphate (ATP) were also measured. In cortical homogenates 5 min of ischemia promoted a diminution in ATP content. Na+,K+-ATPase activity diminished after 40 min and AP after 100 min of ischemia. Na+,K+-ATPase activity in the Percoll gradient fractions after 5 min peaked at a higher density and was significantly decreased after 40 min. AP activity was decreased in typically enriched apical membranes after both times of ischemia. At each time studied Na+,K+-ATPase abundance was increased in cortical homogenates and membranes. Our results showed opposite effects of ischemia on Na+,K+-ATPase activity and abundance. Increased levels of Na+,K+-ATPase protein were observed. The enzyme would be rapidly delivered to membrane domains and become inactivated as ischemia persists.
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PMID:Cortical Na+,K+-ATPase activity, abundance and distribution after in vivo renal ischemia without reperfusion in rats. 1152 37

Experiments were conducted to determine conditions essential for electrophoretic characterization of a detergent-extracted plasma membrane fraction from corn (Zea mays L.) roots. Sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE) initially gave poor resolution of polypeptides in the plasma membrane fraction and, upon detergent treatment for purification of the proton-pumping adenosine triphosphatase (ATPase), showed no enrichment for a 100 kilodalton catalytic subunit characteristic of the ATPase. In contrast to SDS-PAGE, phenol urea acetic acid (PAU)-PAGE clearly resolved two polypeptides in the 100 kilodalton region that were enriched during detergent treatment and indicated at least one polypeptide forms a phosphorylated intermediate characteristic of the ATPase. Problems with SDS-PAGE were found to be caused, in part, by a combination of endogenous proteases and heat-induced aggregation of high molecular weight proteins. The usually standard procedure of boiling the sample prior to SDS-PAGE caused the aggregation of the 100 kilodalton polypeptides. By controlling for proteases using chymostatin and/or phenylmethane sulfonyl floride, and not boiling the sample prior to electrophoresis, two polypeptides were clearly resolved by SDS-PAGE in the 100 kilodalton region of Triton X-114-extracted membranes from corn, oat, barley, and tomato.
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PMID:Electrophoretic characterization of a detergent-treated plasma membrane fraction from corn roots. 1666 34


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