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)

[14C]Estradiol, [14C]estrone, [14C]progesterone and [3H]prostaglandins (PGs) E2 and F2 alpha, when incubated with myometrial plasma membranes (MPM) at a concentration of 1 X 10(-6) M for 1 h at 37 degrees C, bind into MPM at pmolar concentrations. Unlabeled steroids inhibited [3H]PGE2 and [3H]PGF2 alpha binding to MPM in a dose-dependent manner. Membrane-bound and free steroids or PGs were found to be essentially unchanged under the present incubation conditions. Ca2+ ions up to 10 mM increased steroid binding into MPM. Molecular interactions between steroids and MPM were assessed by measuring the steady-state fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), and by estimating the changes in the allosteric properties of MPM-bound (Na+ + K+)ATPase by fluoride (F-). Steroids appear to increase the MPM fluidity, evaluated through changes in the Hill coefficient for MPM-bound (Na+ + K+)ATPase by F- and by the fluorescence polarization method. Binding of sex steroids to MPM increased the membrane fluidity and decreased the binding of the uterus stimulatory PGs by membrane receptors. These studies provide a basis for postulating that a 'non-genomic' mechanism of sex steroids induces reduction of uterine contractions.
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PMID:Sex steroid and prostaglandin interactions upon the purified rat myometrial plasma membranes. 301 59

The contraction of the rat uterus incubated in Ca-free EDTA-containing solution in response to PGE1, oxytocin and vanadate has been investigated in order to examine the mechanism of the release of Ca from intracellular stores. The results obtained show that PGE1 evoked a sustained contraction the magnitude of which diminishes slightly after successive additions of PGE1 but not after long exposure to Ca-free medium. Oxytocin induced two different contractions: one of them was transient and observed only after incubating for 5 min in Ca-free solution; the other remained constant during prolonged incubation in Ca-free medium. Vanadate, an inhibitor of Ca-ATPase, induced sustained contraction after prolonged exposure to Ca-free medium, and isoprenaline, which stimulates Ca re-uptake by intracellular organelles, counteracted the sustained contractile response induced by the three agonists.
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PMID:A comparison of uterine contraction induced by PGE1 and oxytocin in Ca-free solution. 312 9

The present investigation probes the intranuclear molecular changes that serve to link the nuclear binding of estradiol with the hormone-stimulated ribonucleoprotein (RNP) transport in the rat uterus. Within 2 min of in vitro exposure of isolated uterine nuclei to 10 nM 17 beta-estradiol a Mg2+-dependent nuclear ATPase becomes activated and reaches its peak activity. This is immediately followed by a phase of ATP resynthesis. This newly synthesized ATP serves as the substrate for the nuclear protein kinases. Cyclic AMP inhibits this ATP resynthesis and, as a consequence, prevents the estradiol-stimulated nuclear protein kinase activity and the exit of the RNP-estradiol complex from the nuclei. cGMP is stimulatory to the estradiol-mediated nuclear ribonucleoprotein transport.
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PMID:Estradiol-stimulated nuclear ribonucleoprotein transport in the rat uterus: a molecular basis. 316 27

Using several electrophoretic procedures, we have compared the forms of myosin and actin in pregnant and non-pregnant uterus of woman, monkey (Macaca fascicularis) and rat. On non-dissociating gels, native myosin of the three species migrates as a single band, of identical mobility independently of the physiological state. Remigration of this band in dissociating conditions shows that it is constituted of two heavy chains of respectively 201 kDa and 205 kDa; the relative proportions of these two bands are different for the three animal species but do not vary during pregnancy. Using two-dimensional gel electrophoresis, we found that the 17-kDa light chain of purified uterus myosin exists under two isoelectric forms, the more acidic one becoming progressively predominant at the end of pregnancy in the human as in the monkey uterus, while we observed no changes in the rat. In two-dimensional gel electrophoresis, actin of human, monkey and rat uterus is present under three isoforms, the most basic one (the gamma form) increasing early in pregnancy in the two primate species but being always the most abundant form in the rat. The ATPase activity of human uterus myosin was found to be similar for the protein extracted from both pregnant and non-pregnant uterus. The changes observed in the 17-kDa light chain and in the actin isoforms might nevertheless participate in the modifications of contractility of the uterus during pregnancy of the primates.
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PMID:Isoforms of myosin and actin in human, monkey and rat myometrium. Comparison of pregnant and non-pregnant uterus proteins. 378 Jul 18

The binding of calcium by isolated sarcoplasmic reticulum from cow uterus was studied. Sarcoplasmic reticulum was prepared by differential centrifugation. Three fractions were obtained: I, sedimented between 2,500-15,000 x g; II at 40,000 x g; and III, at 150,000 x g. Fraction II was further purified on a sucrose density gradient. All three fractions contained considerable amounts of intrinsic calcium, mostly in fraction I. Calcium binding in the presence of ATP(1) and Mg also was greatest in fraction I, followed by fraction II, with less in fraction III. Without ATP no calcium was taken up. 5 and 10 mM sodium azide partially inhibited calcium binding in fraction I, but not in fraction II, suggesting the presence of some mitochondria or mitochondrial fragments in fraction I. Calcium binding in fraction II was completely inhibited by 3 mM salyrgan; this fraction thus appears to be sarcoplasmic reticulum. ATPase activity was found in all three fractions, highest in fraction II. It is computed that calcium binding in fractions I and II, on the basis of a 50% yield of protein, is sufficient to elicit contraction by supplying calcium to the contractile proteins of the smooth muscle cell and to regulate relaxation and contraction.
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PMID:Role of calcium binding by sarcoplasmic reticulum in the contraction and relaxation of uterine smooth muscle. 423 59

CONTRACTING GRANULATION TISSUES CONTAIN FIBROBLASTS THAT DEVELOP CHARACTERISTICS TYPICAL OF SMOOTH MUSCLE: (a) They contain an extensive cytoplasmic fibrillar system. (b) They show immunofluorescent labeling of their cytoplasm with human anti-smooth muscle serum. (c) The nuclei show complicated folds and indentations, indicative of cellular contraction. (d) There are cell-to-cell and cell-to-stroma attachments. (e) It is possible to extract similar quantities of actomyosin (having the same adenosine triphosphatase activity) from granulation tissue and from pregnant rat uterus. (f) Strips of granulation tissue, when tested pharmacologically in vitro, behave similarly to smooth muscle. All these data support the view that, under certain conditions, fibroblasts can differentiate into a cell type structurally and functionally similar to smooth muscle and that this cell, the "myo-fibroblast," plays an important role in connective tissue contraction.
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PMID:Granulation tissue as a contractile organ. A study of structure and function. 433 23

Non-specific and specific phosphatases have been histochemically localized in the tissues of Avitellina lahorea, an intestinal parasite of sheep and goats. Large quantities of acid phosphatase, alkaline phosphatase and adenosine triphosphatase were observed in almost all organs except the parenchyma where there were moderate amounts of acid phosphatase and no alkaline phosphatase; the reproductive ducts contained moderate amounts of alkaline phosphatase. 5-nucleotidase was observed only in the uterus, egg pouches and eggs and glucose-6-phosphatase activity was restricted to the tegument. The probable functions of these moieties at different sites are discussed.
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PMID:Histochemical localization of phosphomonoesterases in Avitellina lahorea Woodland, 1927 (Cestoda: Anoplocephalida). 608 41

Stimulation of Mg2+, Ca2+ and Mg2+HCO-3 dependent ATPase activity in mitochondrial and microsomal fractions from the uteri of laying hens is demonstrated. ATPase activity was greatest with 5 mM concentrations of Mg2+ at pH 8.5, and at pH 7.4-7.8 following the addition of bicarbonate. Suppression of eggshell calcification, induced by insertion of a thread into the uterus, did not alter Mg2+, Ca2+ and Mg2+HCO-3 ATPase activities. Alkaline phosphatase activity was generally low, and was unaffected by suppression of eggshell calcification. Levels of carbonic anhydrase and calcium binding protein were lower in the uteri of hens laying shell-less eggs. Injections of 1,25(OH)2D3 in hens laying shell-less eggs did not alter CaBP levels or enzyme activities. It is concluded that factors other than 1,25(OH)2D3 and gonadal hormones are involved in the regulation of uterine CaBP levels.
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PMID:Effects of suppression of eggshell calcification and of 1,25(OH)2D3 on Mg2+, Ca2+ and Mg2+HCO-3 ATPase, alkaline phosphatase, carbonic anhydrase and CaBP levels--I. The laying hen uterus. 614 58

An endogenous inhibitor of the Na,K pump, postulated to be involved in the etiology of some hypertensive states, has been reported in extracts of mammalian brain. This encouraged us to test its effects on arterial muscles. An acid-acetone extract of guinea pig brain inhibited Na,K-ATPase derived from canine kidney and evoked responses in arterial strips similar to those produced by ouabain. Unlike ouabain, however, it did not prevent muscles in K-free solutions from relaxing when K was re-added. Bioassays on strips of arteries, uterus and portal vein indicated that the extract did not contain sufficient concentrations of norepinephrine, dopamine, serotonin, prostaglandins, angiotensin II, oxytocin or the Na,K-ATPase inhibitor to account for the observed vascular effects. This could not be said of vasopressin. Furthermore, vasopressin and the vasoactive component of the extract were equally sensitive to several peptidases, and conditions which cleave disulfide bridges. A radioimmunoassay verified that the extract contained sufficient vasopressin to cause contractions. Vasopressin did not inhibit the kidney Na,K-ATPase activity. Finally, the Na,K-ATPase inhibitor, but not the vasoactive substance, was present in extracts of vasopressin-deficient Brattleboro rat brains. Therefore, the Na,K-ATPase inhibitor and the vasoactive substance in these extracts were distinctly different.
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PMID:Identification of a vasoactive substance (vasopressin) in a brain extract containing an unknown inhibitor of Na,K-ATPase. 626 68

A new potent vasodilator, nicardipine hydrochloride inhibited oxytocin-induced contraction of rat uterus dose-dependently with an increase in the intracellular cyclic AMP level at the onset of relaxation. Dibutyryl cyclic AMP and papaverine, an inhibitor of cyclic AMP phosphodiesterase (PDEase), also inhibited the contraction. Nicardipine inhibited competitively PDEase in homogenates of rat uterus which exhibited apparently two Km values for cyclic AMP (3.6 micro M and 67.3 micro M) with the Ki of 5.3 micro M and 13.2 micro M, respectively, but had no effect on adenylate cyclase. Nicardipine enhanced calcium uptake by rat uterine microsomes, at concentrations which inhibited oxytocin-induced contraction in the same manner as cyclic AMP. The maximal stimulation by nicardipine of the microsomal calcium uptake was identical substantially to that by cyclic AMP, and both were not additive. Cyclic AMP was also accumulated during the uptake reaction in the presence of nicardipine. On the contrary, neither myosin ATPase nor microsomal Ca2+-dependent ATPase was inhibited directly by nicardipine. These results suggest that the inhibition of oxytocin-induced contraction of rat uterus by nicardipine may be due to an enhancement of microsomal calcium uptake, mediated by cyclic AMP accumulated through the inhibition of PDEase.
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PMID:A possible mechanism for relaxation of rat uterine smooth muscle by nicardipine hydrochloride (YC-93), a new potent vasodilator. 627 30


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