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)

The Ca2+/Mg2+ ATPase of the rat heart sarcolemmal particles was solubilized with Triton X-100 after treating the membranes with trypsin and purified by high speed centrifugation, ammonium sulfate fractionation, hydrophobic chromatography and gel filtration. The purified enzyme was seen as a single protein band in non-denaturing polyacrylamide gel electrophoresis and its molecular weight by gel filtration was found to be about 240,000. The enzyme utilized Ca-ATP or Mg-ATP as a substrate with high affinity sites (Km = 0.12-0.16 mM) and low affinity sites (Km = 1 mM). The enzyme also utilized CTP, GTP, ITP, UTP and ADP as substrates but at a lower rate in comparison to ATP. The enzyme was activated by Ca2+ (Ka = 0.4 mM) and Mg2+ (Ka = 0.2 mM) as well as by other cations in the order Ca2+ greater than Mg2+ greater than Mn2+ greater than Sr2+ greater than Ba2+ greater than Ni2+ greater than Cu2+. The ATPase activity in the presence of Ca2+ was markedly inhibited by Mg2+, Mn2+, Ni2+ and Cu2+ whereas the monovalent cations such as Na+ and K+ were without effect. The enzyme did not exhibit Ca2+ stimulated Mg2+ dependent ATPase activity and was insensitive to calmodulin, ouabain, verapamil, D-600, oligomycin, azide and vanadate. Optimum pH for Ca2+ or Mg2+ ATPase activity was 8.5-9.0. In view of the possible ectoenzyme nature of the ATPase, its role in adenine nucleotide and Ca2+ metabolism in the myocardium is discussed.
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PMID:Purification and characterization of a Ca2+/Mg2+ ecto-ATPase from rat heart sarcolemma. 297 73

A population of gastric membrane vesicles of high K+ permeability and of lower density than endoplasmic tubulovesicles containing (H+-K+)-ATPase was detected in gastric mucosal microsomes from the rat fasted overnight. The K+-transport activity as measured with 86RbCl uptake had a Km for Rb+ of 0.58 +/- 0.11 mM and a Vmax of 13.7 +/- 1.9 nmol/min X mg of protein. The 86Rb uptake was reduced by 40% upon substituting Cl- with SO2-4 and inhibited noncompetitively by ATP and vanadate with a Ki of 3 and 30 microM, respectively; vanadate also inhibited rat gastric (H+-K+)-ATPase but with a Ki of 0.03 microM. Carbachol or histamine stimulation decreased the population of the K+-permeable light membrane vesicles, at the same time increased K+-transport activity in the heavy, presumably apical membranes of gastric parietal cells, and enabled the heavy microsomes to accumulate H+ ions in the presence of ATP and KCl without valinomycin. The secretagogue-induced shift of K+ permeability was blocked by cimetidine, a H2-receptor antagonist. Four characteristics of the K+ permeability as measured with 86RbCl were common in the resting light and the carbachol-stimulated heavy microsomes; (a) Km for +Rb, (b) anion sensitivity (Cl- greater than SO2-4), (c) potency of various divalent cations (Hg2+, Cu2+, Cd2+, and Zn2+) to inhibit Rb+ uptake, and (d) inhibitory effect of ATP, although the nucleotide sensitivity was latent in the stimulated heavy microsomes. The Vmax for 86RbCl uptake was about 10 times greater in the resting light than the stimulated heavy microsomes. These observations led us to propose that secretagogue stimulation induces the insertion of not only the tubulovesicles containing (H+-K+)-ATPase, but also the light membrane vesicles containing KCl transporter into the heavy apical membranes of gastric parietal cells.
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PMID:Studies on K+ permeability of rat gastric microsomes. 299 Dec 47

A protein tyrosine kinase that phosphorylates both alpha and beta subunits of inactivated (Na+,K+)-ATPase from dog kidney was purified about 500-fold from Ehrlich ascites tumor cell membranes. The enzyme required divalent cations Mn2+, Mg2+, or Fe2+ but was inhibited by Cu2+ or Zn2+. The purified enzyme phosphorylated the beta subunit about five times faster than the alpha subunit of the (Na+,K+)-ATPase. The random polymer poly(Glu80Tyr20) was an excellent substrate while casein was only marginally phosphorylated. In contrast, the purified transforming gene product of Rous sarcoma virus phosphorylated all three substrates and the (Na+,K+)-ATPase was preferentially phosphorylated on the alpha subunit. The transforming gene product of Fujinami sarcoma visue and EGF receptor kinase from A431 cells phosphorylated (Na+,K+)-ATPase poorly whereas casein was an excellent substrate. The molecular weight of the partially purified protein tyrosine kinase from Ehrlich ascites tumor cells determined by gel filtration was about 60,000. One of two major phosphorylated phosphopeptides resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis had an Mr of 60 kDa, thus suggesting that it might be the autophosphorylated protein tyrosine kinase. A phosphatase that hydrolyzes phosphorylated histones or poly(Glu80Tyr20) was partially purified from the same membrane.
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PMID:A tyrosine-specific protein kinase from Ehrlich ascites tumor cells. 302 71

Zinc, copper and lead are known as inhibitory trace metals against brain (Na+-K+)-ATPase. Alcohol (4 g/kg intraperitoneally for 10 days, to rats) induced an elevated level of lead in the cerebral cortex and cerebellum, whereas that of zinc was elevated only in latter region. Copper levels were found to be decreased in the hippocampus, amygdala and hypothalamus, but increased in the spinal cord. Zinc and lead contents were decreased in the amygdala and hypothalamus. The activity of (Na+-K+)-ATPase was enhanced in the hippocampus, amygdala and hypothalamus, but inhibited in the cerebral cortex and cerebellum. It is suggested that alcohol acts differentially on brain zinc, copper and lead concentrations and (Na+-K+)-ATPase activity.
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PMID:Regional distribution of zinc, copper and lead in brain: (Na+-K+)-adenosine triphosphatase correlates of ethanol administration. 302 40

Ferrous iron uptake studies in Bifidobacterium bifidum var. pennsylvanicus were carried out in a well-defined salt solution termed "modified Hanks solution" at both high iron concentrations (LAFIUS conditions) and low concentrations (HAFIUS conditions). Various divalent metals, Mn2+, Zn2+, Ni2+ and Cu2+, inhibited iron uptake under HAFIUS conditions in a non-competitive manner, and in a pseudo-competitive manner under LAFIUS conditions. Cr2+ had no effect. Co2+ inhibited iron uptake competitively under HAFIUS conditions. Metabolic affectors that inhibited iron uptake both under HAFIUS and LAFIUS conditions were: tetraphenylphosphonium chloride, diethylstilbesterol, vanadate, carbonylcyanide-m-chlorophenyl-hydrazone, and a mixture of valinomycin and nigericin. Substances that stimulated iron uptake were KCl, valinomycin, and nigericin. Iron uptake under LAFIUS conditions in piperazine-buffered modified Hanks solution was higher than that in the acetate-buffered solution, and acetate inhibited iron uptake in the piperazine buffer. HAFIUS showed no difference. It is concluded that iron uptake in bifidobacteria is driven by an ATPase-dependent proton-motive force and that both the pH gradient and membrane potential are involved in this process. Mn2+, Zn2+, Ni2+, and Cu2+ may be transported via LAFIUS, but not HAFIUS. HAFIUS may transport only Co2+ in addition to Fe2+.
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PMID:Ferrous iron uptake by Bifidobacterium bifidum var. pennsylvanicus: the effect of metals and metabolic inhibitors. 303 34

Comparisons were made of the histochemical characteristics of skeletal muscle from 10 animal species. The basic comparison was made from the staining patterns for the myofibrillar actomyosin ATPase produced by preincubation of fresh frozen cross-sections of muscle at alkaline pH (10.30) or acid pH (4.60) with those produced by preincubation in media containing Cu2+ at alkaline pH (10.30), near neutral pH (7.40), or acid pH (4.60). Muscle sections were also stained for reduced nicotinamide adenine dinucleotide tetrazolium reductase and alpha-glycerophosphate dehydrogenase to provide an indication of the relative oxidative and glycolytic capacity of the different fiber types. Type II fibers in mixed fibered muscles were either very sensitive, moderately sensitive, or relatively insensitive to inactivation of the myofibrillar actomyosin ATPase after acid preincubation. These fibers were identified as type IIA1, IIA2, and IIA3, respectively. The myofibrillar actomyosin ATPase of the type I fibers of these muscles, with the exception of those in mouse muscle, was activated by pretreatment with acid. A separation of animal species was possible based on the stability of the IIA1 fibers to inclusion of Cu2+ in the preincubation medium. For one group of animals (rat, mouse, monkey, man, dog, rabbit, and cow), a reciprocal relationship existed between lability to acid and stability to Cu2+ for type IIA1 and IIA3 fibers, respectively. For the second group of animals (horse, ass, and cat) there was a parallel relationship between lability or stability of the type IIA1 and IIA3 fibers to pretreatment with either acid or Cu2+.
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PMID:Comparison of fiber types in skeletal muscles from ten animal species based on sensitivity of the myofibrillar actomyosin ATPase to acid or copper. 315 28

Copper (Cu) and PGE2 are known to stimulate LHRH release from explants of the median eminence area (MEA) by two mechanisms distinguishable by their Ca2+ dependence. Moreover, exposure to Cu and PGE2 results in an amplified release of LHRH which is partially Ca2+ dependent, thus, resembling the release process stimulated by PGE2 alone. We have shown that LHRH release stimulated by Cu alone is Na+/Cl- dependent. By defining the Na+/Cl- dependence of PGE2- and Cu/PGE2-stimulated release of LHRH, we wished to ascertain if there is synergism between Cu and PGE2 actions. MEA of adult male rats were incubated for 5 min with 150 microM Cu and then for 15 min with 10 microM PGE2 (Cu/PGE2). Controls were incubated with Cu or PGE2. LHRH release into the medium was evaluated by RIA. Substituting Cl- in the incubation buffer with the non-permeant anion, isethionate, did not alter PGE2 stimulation of LHRH release, but it drastically inhibited Cu/PGE2 stimulation of LHRH release, indicating that this process requires a permeant monovalent anion. PGE2 and Cu/PGE2 stimulation of LHRH release were both inhibited when Na+ was substituted with Li+, or when 0.5 mM ouabain was included in the Na+-containing buffer; neither 10 microM tetrodotoxin (TTX) nor 100 microM amiloride were inhibitory. To ascertain if Na+ is required for Cu uptake, we evaluated the uptake of 67Cu by MEA explants and found that neither ouabain nor Li+ inhibited uptake, indicating that the extracellular Na+ and the activity of Na+/K+ ATPase are required for the process of LHRH release.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Evidence for synergism between copper and prostaglandin E2 in stimulating the release of gonadotropin-releasing hormone from median eminence explants: Na+/Cl- requirements. 328 21

This paper confirmed the reality of the mitochondrial myosin (mt-myosin in human and rat liver. Simultaneously, cytoplasmic myosin (cp-myosin) was prepared from the large particle-free supernatant. The yield of purified mt- and cp-myosin from 1 kg fresh liver was altogether 5-600 mg (= 1-1.2 mumol). Half of the myosin originated from the mitochondrial fraction (composed of about 60 g of mitochondrial protein), while the remaining portion (cp-myosin) was derived from a translucent, but voluminous supernatant (containing about two-third of liver proteins). Comparing the molecular mass of mt- and cp-myosin to the skeletal muscle myosin (about 480 kDa)--on the basis of gel filtration profiles--they proved to have similar profiles. The characteristic properties of both preparations were similar to other myosins developing filamentous aggregations and showing ATP-induced superprecipitations, but they had lower ATPase activities thus being more similar to smooth muscle and cell myosins than to skeletal muscle myosin. The mitochondria and both myosins contained abundant covalently bound P and their endogeneous Si content was low, 2-3 mumol/g in fresh mitochondria and 5-7 mol Si per mol in the mt-myosin. The Si content was resolved into 2-3, while P into 5-6 fractions as revealed by ion exchange chromatographic technique. The mt-myosin could be saturated to a higher P level by autophosphorylation than the cytoplasmic myosin. The interaction of actin with myosin induced a release of significant amounts of P, depending on the ATP concentration. The Cu2+ treatment of mt-myosin caused also P release, and a limited amount of Cu remained bound in the preparations.
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PMID:Preparation and characterization of mitochondrial myosins of rat and human liver. 342 30

Astroglia are implicated in the pathogenesis of lead (Pb) neurotoxicity in two capacities: as a lead sink that sequesters lead and as a target for direct cellular damage. A proposed cellular mechanism of Pb neurotoxicity is the alteration of metal concentrations, particularly the intracellular accumulation of Cu2+. We measured Pb uptake and the effects of Pb acetate on intracellular trace metal concentrations in astroglial cultures prepared from 0- to 4-day-old rat cerebral hemispheres. Mature Sprague Dawley and immature Wistar rat astroglia in culture took up lead from the medium. This finding replicates in vitro the finding reported by others that astroglia in the brain take up Pb. Intracellular Cu and Fe concentrations (micrograms per 2 x 10(6) cells) were increased fourfold or more by treatment with 100 microM Pb for 3 days in the cultures of immature astroglia. Cu levels were also increased twofold or more in mature astroglia treated for 1-3 days with 100 microM Pb. The significance of this finding is that Cu is a potent inhibitor of Na+, K+-ATPase, an enzyme by which astroglia are thought to remove K+ from the extracellular fluid in the brain. Thus, this finding supports the hypothesis that elevated [Cu], and perhaps [Fe], is a subcellular mechanism of neurotoxicity.
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PMID:Effects of lead treatment on intracellular iron and copper concentrations in cultured astroglia. 350 35

The effects of zinc on the enzymes of femoral tissue were investigated in weanling rats that had been given zinc sulfate (1.0 mg Zn2+/100 g body wt) p.o. for 3 days. Administration of zinc caused a marked elevation of alkaline phosphatase and acid phosphatase activities, whereas it did not cause significant changes in succinate dehydrogenase, 5'-nucleotidase, ATPase, pyrophosphatase and beta-N-acetylglucosaminidase activities. The effect of zinc was greater on alkaline phosphatase of the femoral diaphysis. Zinc content of the femoral diaphysis was raised significantly by administration of zinc. The addition of zinc in concentrations of 10(-2)-10(2) microM did not produce a significant increase in alkaline phosphatase activity in the femoral diaphysis, indicating that zinc could not activate the enzyme. Administration of cycloheximide or actinomycin D completely inhibited the increase in alkaline phosphatase activity produced by administration of zinc. DNA content of the femoral diaphysis, but not epiphysis, was increased markedly by administration of zinc. The increases in both alkaline phosphatase activity and DNA content of the femoral diaphysis were not caused by administration of copper, manganese, cobalt, nickel and chromium(III). The present investigation suggests that zinc may induce the increase in alkaline phosphatase related to DNA synthesis and, as a result, stimulate bone growth.
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PMID:Action of zinc on bone metabolism in rats. Increases in alkaline phosphatase activity and DNA content. 395 86


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