Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To investigate whether 'aldosterone-induced proteins' could be detected in mammalian species, cultured renal collecting duct epithelia from neonatal rabbit kidneys were labelled under aldosterone administration with radioactive methionine and subsequently fractionated into cytosolic and coarse membrane protein fractions. Newly synthesized proteins were then analyzed by SDS-PAGE, isoelectric focussing and two-dimensional electrophoresis. Quantitative estimates of individual newly synthesized proteins were performed utilizing gel slicing, scintillation counting and autoradiography. The labelling experiments demonstrated that, in comparison to controls, aldosterone (1 X 10(-6) M) generally increased the amount of radioactive protein. No qualitative changes in the pattern of newly synthesized proteins and, therefore, no classical aldosterone-induced proteins were observed. The increase of radioactive protein was already seen after 1, 6, and 18 h of hormone treatment. The effect could be blocked partially by spironolactone (1.5 X 10(-4) M), and totally by amiloride (1 X 10(-6) M), g-strophantin (5 X 10(-4) M), and cycloheximide (1 X 10(-6) M. Thus, the interference of aldosterone action at the receptor level, the Na+ channels and the Na+/K(+)-ATPase pump demonstrate that the expression of proteins in cultured renal collecting duct cells is a sensitive system and seems to be controlled by aldosterone at the receptor level, but also counter-controlled by specific plasma membrane sites.
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PMID:Action of aldosterone on protein expression in cultured collecting duct cells from neonatal rabbit kidney. 261 84

Homogeneous preparations of actin cleaved into two fragments, the N-terminal 9- and C-terminal 36-kDa peptides, were achieved by proteolysis of G-actin with subtilisin at 23 degrees C at a 1:1000 (w/w) ratio of enzyme to actin. The subtilisin cleavage site was identified by sequence analysis to be between Met-47 and Gly-48. Although under nondenaturing conditions the two fragments remained associated to one another, the cleavage affected macromolecular interactions of actin. The rates of cleaved actin polymerization by MgCl2, KCl, and myosin subfragment 1 (S-1) were slower and the critical concentrations for this process were higher than in intact protein. Intact and cleaved actin formed morphologically indistinguishable filaments and copolymerized in the presence of MgCl2. The affinity of actin for S-1 was decreased by about 10-fold due to subtilisin cleavage, but the S-1 ATPase activity was activated to the same Vmax value by both intact and cleaved actins. DNase I inhibition measurements revealed lower affinity of cleaved actin for DNase I than that of intact protein. These results are discussed in terms of actin's structure.
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PMID:Subtilisin-cleaved actin: polymerization and interaction with myosin subfragment 1. 267 52

Recently a number of possible functions for ergothioneine (ERT) have been suggested (1). This paper elaborates on some of these in light of overlooked or recent publications and presents additional hypotheses including: 1. Reduced ERT (ergothionol) may be an acyl carrier. 2. ERT, in conjunction with thyroid hormone and iodine, may be a cofactor in peroxidative and oxidative reactions. 3. ERT and thyroid hormone may be required for the oxidation of reduced pyridine nucleotides and the coupling of this to oxygen consumption (respiration) and ATP generation/ATPase action (heat production). 4. ERT may be required for both gene expression and repair. 5. 2-Thioimidazoles (ERT and 2-thiourocanic acid in particular) may be immunoregulatory. 6. ERT may be involved in the protection from oxidation (inactivation) of methionine and methionine containing chemoattractants, hormones, tRNA, etc. Some future research activities are suggested.
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PMID:In search of a physiological function for L-ergothioneine--II. 267 18

The present study demonstrates that morphine (10(-6) and 10(-5) M), methionine-enkephalin or leucine-enkephalin (10(-10), 10(-8), and 10(-6) M) were able to inhibit significantly, in a dose-dependent manner, both the sarcolemmal Ca2+-dependent ATPase and the ouabain-sensitive Na+-K+ ATPase activities. The inhibitory action of these opioids on the two ATPases was not antagonized by preincubation with naloxone (10(-6) M). Naloxone alone (10(-8), 10(-6) and 10(-5) M) did not affect both the sarcolemmal Ca2+-dependent ATPase and the ouabain-sensitive Na+-K+ ATPase activities. Heat-denatured methionine-enkephalin (10(-6) M) or leucine-enkephalin (10(-6) M) also unaffected both the ATPases. The possibility is also discussed that opioid peptides may regulate myocardial contractility by modulating the movement of ions across the heart sarcolemma.
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PMID:Inhibitory action of opioid peptides on ouabain-sensitive Na+-K+ and Ca2+-dependent ATPase activities in bovine cardiac sarcolemma. 281 34

Normal rat liver lysosomal membranes in the form of membrane vesicles have been purified using Percoll density gradient centrifugation. Lysosomes (density = 1.111) were purified approximately 63 +/- 12-fold (mean +/- standard deviation, n = 5) using a gradient of Percoll made isotonic with sucrose and buffered to pH 7.0. These lysosomes were then exposed to 10 mM methionine methyl ester, pH 7.0, the uptake of which resulted in swelling and breakage of the lysosomes with subsequent vesicle formation. These vesicles (density = 1.056) were further separated from residual mitochondrial and plasma membrane enzyme activities using a second Percoll density gradient. Marker enzyme analysis and electron microscopy indicated that the lysosomal membranes were essentially free of both beta-hexosaminidase, a soluble lysosomal enzyme, and contaminating organelles. The specific activity of lysosomal ATPase in the lysosomal membranes was fourfold greater than in the intact lysosomes.
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PMID:Isolation of highly purified rat liver lysosomal membranes using two Percoll gradients. 282 36

The protease sensitivity of the catalytic alpha-subunit of Na,K-ATPase during intracellular transport along the exocytic pathway has been investigated in two amphibian epithelial cell lines. Controlled trypsinolysis followed by immunoprecipitation of cell homogenates or microsomal fractions from [35S]methionine pulse-chased A6 kidney cells revealed distinct cleavage patterns by SDS-PAGE. Shortly after synthesis (7-min pulse), the 98-kD alpha-subunit is fully sensitive to trypsin digestion and is cleaved into a 35-kD membrane-bound and a 27.5-kD soluble peptide. With a 15-min pulse, 10% of the newly synthesized polypeptide becomes resistant to trypsin digestion. With longer chase time, the proportion of protease-resistant alpha-subunit further increases. Concomitantly, the alpha-subunit acquires the ability to undergo cation-dependent conformational transitions, as reflected by distinct tryptic digest patterns in the presence of Na+ or K+. Similar results were obtained in TBM cells, a toad bladder cell line. Our data indicate that the catalytic subunit of Na,K-ATPase is structurally rearranged during intracellular transport from its site of synthesis to its site of action at the cell surface, a modification which might mark the functional maturation of the enzyme.
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PMID:Maturation of the catalytic alpha-subunit of Na,K-ATPase during intracellular transport. 282 91

The egg white of marine turtle (Caretta caretta Linn.) and one species of tortoise (Geomyda trijuga trijuga Schariggar) contain a low molecular weight basic protein. It has been purified to homogeneity from the egg white of marine turtle and characterized in terms of its major physicochemical and chemical properties. The molecular weight of this protein calculated from gel filtration, sodium dodecyl sulfate-gel electrophoresis in the presence of urea, sedimentation-diffusion data, and amino acid composition is 4300. Its isoelectric point is at pH 11.1 and intrinsic viscosity is 0.038 dl g-1 in 0.2 M NaCl. It has a Stokes radius of 12.6 A and a diffusion coefficient of 16.50 x 10(-7) cm2 s-1. Analysis of the far-ultraviolet circular dichroic spectrum has shown that the basic protein contains 27% beta-pleated sheet and little or no alpha-helix. It possesses a single polypeptide chain of 40 amino acid residues with three disulfide bonds. It lacks serine, methionine, phenylalanine and carbohydrate moiety. It binds to DNA and stimulates ATPase activity due to its strong basicity. The complex of DNA-basis protein is partially resistant to the action of DNase.
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PMID:Purification and characterization of a low molecular weight basic protein from marine turtle egg white. 283 72

Aldosterone induces the synthesis of a group of glycoproteins (GP65,70) in toad urinary bladders which are potential effectors of the natriferic action of this hormone. In the present study we have confirmed that aldosterone produces a two-phase electrophysiological response. During the early phase (less than 3 h) short-circuit current and transepithelial conductance increase in parallel, while during the late phase (greater than 3 h) short-circuit current continues to increase without any further change in conductance. By biosynthetically labeling aldosterone-treated toad bladders with [35S]methionine either during the early (h 0-2 or 1-3) or the late (h 4-6 or 7-9) phases of the natriferic response, we have demonstrated that GP65,70 is synthesized as a late effect of aldosterone. Since synthesis of GP65,70 occurs at a time when the electromotive force of the Na+ pump is increasing, and since GP65,70 biochemically resembles the beta subunit of Na+/K+-ATPase, studies were undertaken to examine whether GP65,70 is the beta subunit. Purified amphibian renal beta subunit was analyzed by two-dimensional polyacrylamide gel electrophoresis and was found to have an isoelectric point and Mr value similar to those of GP65,70. However, when nitrocellulose blots containing wheat germ agglutinin-purified proteins from aldosterone-treated bladders were stained with monospecific polyclonal antibodies developed against the beta subunit, GP65,70 was not recognized, whereas a group of slightly more acidic proteins of similar Mr were recognized. Thus, GP65,70 is not the beta subunit of Na+/Ka+-ATPase. Further studies are needed to determine the cellular function of GP65,70.
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PMID:Aldosterone-induced glycoproteins: electrophysiological-biochemical correlation. 283 98

Rat colonic basolateral membranes were incubated with S-adenosyl-L-[methyl-3H]methionine (0.3 mM) at 37 degrees C for 2 h at pH 9.0. This resulted in an increase in the specific activity of Na+ + K+-ATPase by 60%. Kinetic parameter analysis revealed a 2-fold increase in the Vmax. of this enzymatic activity, whereas the Km for ATP was unchanged. The methylation inhibitor S-adenosyl-L-homocysteine (2 mM) significantly reduced these S-adenosyl-L-methionine-stimulated increases in specific activity and the Vmax. of Na+ + K+-ATPase. S-Adenosyl-L-methionine treatment of basolateral membranes was also found to significantly increase the fluidity of these preparations, as assessed by steady-state fluorescence polarization techniques using the fluorophore 1,6-diphenyl-1,3,5-hexatriene; S-adenosyl-L-homocysteine (2 mM) again markedly reduced this S-adenosyl-L-methionine-induced increase in fluidity. While transmethylation reactions involving phospholipids, non-polar lipids and proteins were all found to exist in rat colonic basolateral membranes, based on a number of observations, the results of the present studies suggest that transmethylation of membrane phospholipids, but not membrane non-polar lipids or proteins, influenced the fluidity of basolateral membranes which, in turn, modified Na+ + K+-ATPase activity in these membranes.
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PMID:S-adenosyl-L-methionine modulates Na+ + K+-ATPase activity in rat colonic basolateral membranes. 283 60

The Na+,K+-ATPase is a basic membrane element in all animal cells that maintain transmembrane gradients of Na+ and K+ ions. When integrated into artificial lipid vesicles the isolated Na+,K+-ATPase is capable of actively transporting Na+ and K+, thus establishing its identity with the well-known Na+ pump. Three isoforms of the catalytic subunit of Na+,K+-ATPase have recently been identified in the rat brain. Elucidating the regulatory processes which govern their biosynthesis in the brain is central to understanding the physiological alterations which accompany diabetes, chronic cardiotonic steroid intoxication and degenerative diseases of the retina. In this study, synthesis of the alpha-1 and alpha-2 isoforms was examined in the retina of rats following intraocular injection of citrate buffer. Incorporation of [35S]methionine into both isoforms was increased 60-100% by 6 hr, demonstrating that neuronal Na+ pump is subject to regulation, although the question of independent regulatory controls remains unanswered.
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PMID:Molecular isoforms of the sodium pump in brain. 284 14


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