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)

The concentration of calcium-binding protein (CaBP) and the activities of calcium adenosine triphosphatase (Ca(2+)-ATPase) and carbonic anhydrase (CA) were determined in the shell gland mucosa of hens in two experiments. In Experiment 1, laying hens on a proprietary layer mash were compared with hens rested from lay by the feeding of whole grain barley. In Experiment 2 comparisons were made of laying hens fed the proprietary layer mash and producing eggs with either strong or weak shells. These latter comparisons were also made when the shell gland was quiescent or active with respect to daily eggshell formation. Feeding whole grain barley reduced egg production to zero after 11 days. This reduction in rate of lay was accompanied by significant reductions in all three markers, the effect on Ca(2+)-ATPase and CaBP being less than for CA. Control values were regained between 10 and 16 days after the barley was replaced with the layer mash. Relative shell strength and the physiological status of the shell gland with respect to time of daily eggshell formation had no significant effect on any marker in Experiment 2.
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PMID:Calcium and carbonate supply in the shell gland of hens laying eggs with strong and weak shells and during and after a rest from lay. 147 May 88

The effect of the calcium-binding protein regucalcin on the Ca2+ transport system in rat liver mitochondria was investigated. Ca2+ transport was assayed by the method of Millipore filtration to estimate mitochondrial 45Ca2+ accumulation. 45Ca2+ uptake was stimulated by the presence of regucalcin (1.0 and 2.0 microM). This stimulation was remarkable during 1.0 min after 45Ca2+ addition, while appreciable stimulation was no longer seen at 3 min. Regucalcin (2.0 microM)-induced stimulation of 45Ca2+ uptake was prevented by the presence of ruthenium red (1.0 microM) and lanthanum chloride (0.1 mM). Regucalcin (2.0 microM) did not increase the mitochondrial adenosine triphosphatase (ATPase) activity during 3.0 min after Ca2+ addition. Meanwhile, 45Ca2+, which accumulated in the mitochondria during 5.0 min after 45Ca2+ addition, was not released by the addition of regucalcin. Regucalcin may stimulate Ca2+ uptake in rat liver mitochondria independently of the energy.
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PMID:Calcium-binding protein regucalcin stimulates the uptake of Ca2+ by rat liver mitochondria. 204 6

The effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on Ca2+-adenosine triphosphatase (ATPase) activity in hepatic microsomes was investigated. Mg2+-ATPase activity was clearly increased by the presence of 50 microM Ca2+. Regucalcin (1.0-4.0 microM) caused a remarkable elevation (about 3-fold) of Ca2+-ATPase activity. Also, Mg2+-ATPase activity was increased (about 1.6-fold) by the presence of regucalcin (2.0 and 4.0 microM). Guanosine-5'-O-(3-thiotriphosphate) (GTPrs; 10(-5) and 10(-4) M) and nicotinamide adenine dinucleotide phosphate oxidized form (NADP+; 10(-5) to 10(-3) M) or reduced form (NADPH; 10(-4) and 10(-3) M) significantly increased Ca2+-ATPase activity. These increases were not enhanced by the presence of regucalcin (2.0 microM). Of various metal ions, a comparatively low concentration of V5+ (10(-5) M) or Cd2+ (10(-6) M) significantly increased Ca2+-ATPase activity, while Hg2+, Zn2+, Cu2+ and Mn2+ did not have such an effect. Regucalcin (2.0 microM) did not enhance the effect of V5+ and Cd2+ on Ca2+-ATPase activity. The present finding, that regucalcin activates hepatic microsomal Ca2+-ATPase, suggests a cell physiological role of regucalcin as an activator in the microsomal Ca2+-pump activity. This action of regucalcin may not be influenced by other regulators.
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PMID:Activation of hepatic microsomal Ca2+-adenosine triphosphatase by calcium-binding protein regucalcin. 252 22

Native thin filaments were extracted from rabbit uterus by the procedure of Marston and Smith. The protein content was actin, tropomyosin, and caldesmon in molar ratios of 1:0.2:0.03. Some filamin, myosin, and calcium-binding protein were also present. The thin filaments activated skeletal or smooth muscle myosin magnesium adenosine triphosphatase at least 30-fold. Activation was regulated by Ca2+; maximum observed Ca2+ sensitivity was greater than 10 times. The thin filaments were dismantled into component proteins by the method of Smith and Marston. Actin and actin-tropomyosin-activated myosin magnesium adenosine triphosphatase, but the activation was not Ca2+-regulated. Added caldesmon inhibited adenosine triphosphatase activation by as much as 80%, with 50% inhibition at 1 caldesmon per 50 actin. Caldesmon inhibition was not Ca2+ dependent, but inhibition could be reversed by further addition of Ca2+ and calmodulin. It is concluded that the thin filaments of uterine smooth muscle are Ca2+ regulated and that this regulatory system could be involved in control of uterine smooth muscle contractility. A mechanism for thin filament regulation, mediated by caldesmon, is proposed.
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PMID:Calcium ion-dependent regulation of uterine smooth muscle thin filaments by caldesmon. 291 89

A particulate fraction of rat intestinal mucosal homogenates, termed the "calcium-binding complex," contains three vitamin D-dependent activities: calcium binding of high affinity, calcium-dependent adenosine triphosphatase, and p-nitrophenylphosphatase. These particulate activities vary concordantly with intestinal calcium transport, suggesting that they represent membrane components of the translocation mechanism. The particulate was solubilized with 1-butanol and the activities were resolved partially by gel filtration and by DEAE-cellulose and spheroidal hydroxyl-apatite column chromatography. The Ca-binding activity was separated from the enzymes and isolated as a protein of molecular weight approximately 200,000, as estimated by gel filtration in 0.1% Triton X-100. The membrane protein, named IMCal (intestinal membrane calcium-binding protein), was dissociated with sodium dodecyl sulfate to yield a monomer of molecular weight 20,500 which is clearly distinguishable from the soluble calcium-binding protein (molecular weight 11,500) of rat mucosa. The apparent dissociation constants of Ca2+ of IMCal and of the soluble calcium-binding protein were estimated as 0.37 microM and 2.25 microM, respectively. The vitamin D-dependent activities of the calcium-binding complex are present in isolated intestinal microvillus membranes and may mediate the translocation of calcium from the intestinal lumen to the cytosol.
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PMID:Intestinal membrane calcium-binding protein. Vitamin D-dependent membrane component of the intestinal calcium transport mechanism. 625 88

19-Nor-1,25-dihydroxyvitamin D(2) (19-norD(2)) a less calcemic and phosphatemic analog of 1,25-dihydroxyvitamin D (1,25[OH](2)D(3)), is approved for the treatment of secondary hyperparathyroidism in patients with kidney failure. We have previously demonstrated that 19-norD(2) is less active than 1,25(OH)(2)D(3) in stimulating bone resorption. In this study, we compared the potencies of 19-norD(2) and 1,25(OH)(2)D(3) in stimulating net calcium and phosphate absorption in the intestine. Mineral balance was assessed in normal rats during the last 4 days of a 14-day treatment with various daily doses of 19-norD(2) or 1,25(OH)(2)D(3). Calcium absorption increased from 16.5% +/- 7.8% in vehicle-treated rats to 27.5% +/- 7.2% in rats given 10 ng/day 1,25(OH)(2)D(3) and to 21.6% +/- 3.9%, 26.2% +/- 5.5%, and 27.4% +/- 5.1% in rats treated with 10, 50, and 100 ng/day 19-norD(2), respectively. Thus comparable stimulation of calcium transport was attained with 10 ng 1,25(OH)(2)D(3) and 100 ng 19-norD(2). Similar results were obtained for phosphate absorption, with an increase from 28.2% +/- 5.5% in vehicle-treated rats to 40.2% +/- 4.7% in rats given 10 ng/day 1,25(OH)(2)D(3) and to 32.9% +/- 2.2%, 36.2% +/- 4.5%, and 36.8% +/- 3.8% in rats given 10, 50, and 100 ng/day 19-norD(2), respectively. Vitamin D compounds are believed to increase calcium absorption by inducing a calcium channel (epithelial calcium transporter or calcium transporter-1 [CaT1]) on the luminal membrane, a calcium-binding protein (Calbindin D9k) in the cytosol, and a calcium pump (plasma membrane calcium adenosine triphosphatase-1 [PMCA1]) on the basolateral membrane. Northern-blot analysis of intestinal ribonucleic acid of vitamin D-deficient rats given seven daily injections of vehicle or 100 ng 1,25(OH)(2)D(3) or 19-norD(2) revealed that 19-norD(2) was less potent than 1,25(OH)(2)D(3) in stimulating expression of CaT1, Calbindin D9k and PMCA1. In summary, the reduced calcemic and phosphatemic activities of 19-norD(2) can be attributed to lower potency in stimulating intestinal calcium and phosphate absorption.
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PMID:Differential effects of 19-nor-1,25-dihydroxyvitamin D(2) and 1,25-dihydroxyvitamin D(3) on intestinal calcium and phosphate transport. 1203 88