Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: HUMANGGP:019083 (5'-nucleotidase)
 3,019 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sarcolemmal vesicles prepared by a new procedure from bovine tracheal smooth muscle were found to have a Na-Ca exchange activity that is significantly higher than that reported for different preparations from other types of smooth muscle. The exchange process system co-purified with 5'-nucleotidase, a plasma membrane marker enzyme, and was significantly enriched (over 100-fold) compared to mitochondria (cytochrome-c oxidase) but only slightly enriched (4-fold) compared to sarcoplasmic reticulum (NADPH-cytochrome-c reductase). The Na+ dependence of Ca2+ transport was demonstrated through both uptake and efflux procedures. The uptake profile with respect to Ca2+ was monotonic with a linear vo VS. vo.S-1 plot. The resultant Km of Ca2+ from the airway sarcolemmal vesicles (20 microM) was similar in magnitude to the Km of cardiac sarcolemmal vesicles (30 microM). Tracheal vesicles demonstrated a Vmax of 0.3-0.5 nmol.mg-1.s-1 which is significantly higher than that reported in preparations from other smooth muscle types. Furthermore, two processes found to stimulate cardiac Na-Ca exchange, pretreatment with either a mixture of dithiothreitol and Fe2+ or with chymotrypsin, were ineffective on the tracheal smooth muscle. Thus, the Na-Ca exchanger identified in tracheal smooth muscle appears to be different from that observed in cardiac muscle, implying that regulation of this activity may also be different.
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PMID:Sodium-calcium exchange in sarcolemmal vesicles from tracheal smooth muscle. 282 16

A venom exonuclease 'phosphodiesterase' (E.C. 3.1.4.1) has been purified from Cerastes cerastes venom by a combination of gel filtration on Sephadex G-100 superfine and ion exchange chromatography on DEAE-Sepharose. The enzyme showed a single band on PAGE and SDS-PAGE and had a molecular weight of 110,000. The final preparation was purified 28 fold. It had no carbohydrate and it did not have protease or 5'-nucleotidase activities. Optimum temperature for enzyme activity was 56 degrees C. The enzyme was rapidly inactivated when pre-incubated above 40 degrees C. Energy of activation (Ea) was calculated to be 0.913. The optimum pH was 9.0. Cysteine, glutathione, dithiothreitol, 2-mercaptoethanol, ADP and AMP inhibited the enzyme. Cysteine caused a non-competitive inhibition, while ADP showed a competitive inhibition. EDTA at a concentration of 0.5 mM caused complete inhibition of the enzyme, which could be reversed by the addition of Ca2+ or Mn2+.
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PMID:Purification and characterization of phosphodiesterase (exonuclease) from Cerastes cerastes (Egyptian sand viper) venom. 282 90

The distribution of hepatic binding sites for the calcium-mobilizing second messenger, inositol 1,4,5-trisphosphate (IP3), was analyzed in subcellular fractions of the rat liver by binding studies with [32P]IP3 and compared with the Ca2+ release elicited by IP3 in each fraction. Three major subcellular fractions enriched in plasma membrane, mitochondria, and endoplasmic reticulum were characterized for their 5'-nucleotidase, glucose-6-phosphatase, succinate reductase, and angiotensin II binding activities. The fraction enriched in plasma membrane showed 7- and 20-fold increases in IP3 binding capacity over those enriched in endoplasmic reticulum and mitochondria, respectively, and contained a single class of high-affinity binding sites with Kd of 1.7 +/- 1.0 nM and concentration of 239 +/- 91 fmol/mg protein. IP3 binding reached equilibrium in 30 min at 0 degrees C, and the half-time of dissociation was about 15 min. The specificity of the IP3 binding sites was indicated by their markedly lower affinities for inositol 1-phosphate, phytic acid, fructose 1,6-bisphosphate, 2,3-bisphosphoglycerate, and inositol 1,3,4,5-tetrakisphosphate. The Ca2+-releasing activity of IP3 in the subcellular fractions was monitored with the fluorescent indicator, Fura-2. All three fractions showed ATP-dependent Ca2+ uptake and rapidly released Ca2+ in response in IP3. The fraction enriched in plasma membrane was the most active in this regard, releasing 174 +/- 67 pmol Ca2+/mg of protein compared to 45 +/- 10 and 48 +/- 7 pmol/mg protein for the fractions enriched in endoplasmic reticulum and mitochondria, respectively. These data suggest that the [32P]IP3 binding sites represent specific intracellular receptors through which IP3 mobilizes Ca2+ from a storage site associated (or co-purifying) with the plasma membrane of the rat liver. It is likely that a specialized vesicular system (to which IP3 can bind and trigger the release of Ca2+) is located in close proximity with the plasma membrane and is thus adjacent to the site at which IP3 is produced during stimulation of the hepatocyte by Ca2+-mobilizing hormones.
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PMID:Characterization of inositol 1,4,5-trisphosphate receptors and calcium mobilization in a hepatic plasma membrane fraction. 283 98

In cultured cells derived from isolated micromeres of sea urchin eggs, H+,K+-ATPase activity, which became detectable simultaneously with the initiation of spicule formation, was localized in the plasma membrane and the microsome fractions. Activities of marker enzymes for plasma membrane, 5'-nucleotidase, Na+,K+-ATPase, and adenylate cyclase, were found to be high in the plasma membrane fraction. Considerable activity of rotenone-insensitive NADPH-cytochrome c reductase, a marker enzyme for microsome, was detectable in the microsome fraction. These fractions exhibited barely any appreciable activity of markers for the other organellae. H+,K+-ATPase in plasma membrane probably mediates H+ release from the cells, in which H+ is produced in overall reaction to form CaCO3, the main component of spicules, from Ca2+, CO2 and H2O. Cl-,HCO3(-)-ATPase activity was also found in these two fractions before and after the initiation of spicule formation. After initiation, the skeletal vacuole fraction was obtained from subcellular structures containing spicules. Considerable activity of Cl-,HCO3(-)-ATPase was observed in this fraction, which exhibited a weak activity of UDP-galactose: N-acetylglucosamine galactosyltransferase, a marker enzyme for Golgi body. Cl-,HCO3(-)-ATPase in the skeletal vacuole membrane probably mediates HCO3- transport into the vacuoles to supply HCO3- for spicule formation.
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PMID:Distributions of H+,K+-ATPase and Cl-,HCO3(-)-ATPase in micromere-derived cells of sea urchin embryos. 283 20

The cellular and subcellular distribution of 5'-nucleotidase in tissues of the electric ray Torpedo marmorata has been investigated by means of an antiserum raised against the native enzyme purified from the electric organ. As revealed by immunohistochemistry the enzyme is associated with the surface of the axons of the electric nerves and of spinal nerves. Using the post-embedding colloidal gold technique at the electron-microscopical level 5'-nucleotidase could be located at the plasma membrane of the Schwann cells including the myelin and the fine processes covering the terminal axon ramifications. Also the perineurial sheath of the axons inside the electric organ is 5'-nucleotidase positive. The plasma membrane of the axon and the terminal axon region or the postsynaptic membrane do not contain 5'-nucleotidase. Immunoprecipitation studies using polyacrylamide beads suggest that the ecto-Ca2+- or -Mg2+-adenosine 5'-triphosphatase previously ascribed to synaptosomes of the Torpedo electric organ is not associated with the same membranes as 5'-nucleotidase. Within the electric organ the dorsal plasma membrane of the electroplaque cell, blood capillaries and the connective tissue layer surrounding the columns of electroplaque cells also bind the antibodies. In central nervous tissue solely blood vessels show immunofluorescence. Within the electric lobe both the surface of the electromotor neurons as well as the myelinated axons giving rise to the electric nerve are negative. This also applies to the axons of the optic nerve suggesting that the antiserum is Schwann cell specific, and does not bind to a potential oligodendroglial 5'-nucleotidase. In peripheral tissue the surface of skeletal muscle fibres as well as that of individual myofibrils bind the anti-5'-nucleotidase antibodies. Our results demonstrate that the Schwann cell plasma membrane, including myelin, contains 5'-nucleotidase and that one can distinguish by means of a specific antiserum between Schwann cell and oligodendroglia plasma membranes. The functional significance of the association of 5'-nucleotidase with Schwann cells along the entire surface of axons including the synaptic region as well as with other parts of the electric tissue is discussed regarding its catalytic activity and also the possibility that this surface glycoprotein may be involved in mediating cellular interactions.
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PMID:Monospecific antiserum against 5'-nucleotidase from Torpedo electric organ: immunocytochemical distribution of the enzyme and its association with Schwann cell membranes. 283 6

Separation of the gradient-purified gastric microsome into two membrane subfractions of distinct enzymatic and phospholipid composition has been achieved by mild SDS (0.033% w/v) treatment followed by sucrose gradient centrifugation of the pig and rabbit gastric microsomes. While the high-density membranes had all of the (H+,K+)-ATPase and K+-pNPPase activities and revealed a single major 100-kDa band on SDS-PAGE, the low-density membranes contained all of the 5'-nucleotidase and nearly all of the Mg2+-ATPase. In the present study, the low-density subfraction has been characterized to be derived from the apical membranes and the high-density one from the intracellular tubulovesicular membranes of the parietal cells. Such characterization was based primarily on sole dependency of the apical plasma membranes on the endogenous activator for (H+,K+)-ATPase activity, differential sensitivity of the activator (AF)-dependent and -independent (H+,K+)-ATPase on micromolar vanadate and Ca2+, specific vitamin B12 binding ability of the apical plasmalemma, phospholipid and protein profiles of the two membrane subfractions, and other parameters. The AF, mentioned previously, has recently been implicated as a cytosolic regulator of the gastric (H+,K+)-ATPase [Bandopadhyay et al. (1987) J. Biol. Chem. 262, 5664-5670]. Two different forms (i.e., AF-dependent and -independent forms) of the (H+,K+)-ATPase are suggested to be present in the tubulovesicles on the basis of differential vanadate sensitivity while the AF-dependent form alone is present in the apical membranes. The data have been discussed in terms of stimulation-induced membrane transformation characteristic of the H+-secreting epithelia including the acid-secreting cells of the stomach.
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PMID:Characteristics of the isolated apical plasmalemma and intracellular tubulovesicles of the gastric acid secreting cells: demonstration of secretagogue-induced membrane mobilization. 285 60

Cyclic AMP has been implicated as a regulator of capacitation, but the control of its metabolism in sperm remains obscure. A recent study of mouse sperm has shown capacitation-related changes in the activities of both adenylate cyclase, which increased during incubation, and cyclic nucleotide phosphodiesterase, which decreased. The present study was conducted to extend these observations by measuring phosphodiesterase activity in sperm incubated in media with modified calcium and/or glucose content, conditions known to modulate fertilizing ability. Phosphodiesterase activity of sequential sperm samples, taken first when sperm are essentially uncapacitated and then when they are either partially or completely capacitated, decreased with time under all conditions, and in each case the greater fall in activity was seen in the medium that would support the greater change in fertilizing ability of the sperm population. Sperm washed by centrifugation to remove epididymal fluid also displayed a reduction in phosphodiesterase activity with time. The medium surrounding the sperm contained about half of the total phosphodiesterase activity, as well as 5'-nucleotidase and adenosine deaminase. The crude enzyme preparation showed complex kinetic behavior when assayed over a range of cAMP concentrations, but the reduction in activity with time was seen at all substrate levels. The observed changes in phosphodiesterase activity, together with the increased adenylate cyclase activity seen under these sperm incubation conditions, would increase cAMP availability with time, thus providing further evidence for a fundamental role for cAMP in controlling the events of capacitation.
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PMID:Phosphodiesterase activity of mouse sperm incubated under conditions that modulate fertilizing potential in vitro. 285 27

Because adenosine plays a role in the regulation of glomerular filtration rate and of the release of renin, we examined the possibility of a local source for this mediator. We found that rat cultured glomerular mesangial cells converted 5'-AMP into adenosine. The properties of the enzyme involved in the reaction were those of an ecto-5' nucleotidase: (1) the products of the reaction were generated in the extracellular fluid although no 5'-nucleotidase was released by the cells into the medium; (2) identical activities were found for cultured cells in situ and sonicated cells; (3) the diazonium salt of sulfanilic acid which is a nonpenetrating reagent inhibited up to 75% of the enzyme activity. Ecto-5'-nucleotidase activity of intact cells obeyed Michaelis-Menten kinetics. Apparent Km for 5'-AMP was 0.32 mM. 5'-UMP was a strictly competitive inhibitor. ADP exerted a very powerful inhibitory effect and behaved also as a competitive inhibitor. ATP was inhibitory both by increasing Km and by decreasing Vmax. Ecto-5'-nucleotidase was active in the absence of divalent cations. However, Mg2+, Ca2+, Co2+ and Mn2+ were stimulatory. Zn2+ and Cu2+ suppressed the activity. Concanavalin A, a plant lectin, was markedly inhibitory, suggesting that a glycoprotein moiety was necessary to express enzyme activity. Ecto-5'-nucleotidase activity was not modified during phagocytosis of serum-treated zymosan by mesangial cells. Rat cultured glomerular epithelial cells exhibited a 5'-nucleotidase activity which was 4 times lower than that of the mesangial cells in primary culture.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Ecto-5'-nucleotidase of cultured rat mesangial cells. 285 4

When the particulate fraction from a rat liver homogenate was incubated with [3H]putrescine and calcium, the radioactive amine was incorporated into the membranes via a transglutaminase-mediated reaction. Fractionation of the membranes by isopycnic density gradient centrifugation revealed that the radioactive label was coincident with the 5'-nucleotidase and transglutaminase activities which serve as markers for the plasma membrane (Slife, C. W., Dorsett, M. D., Bouquett, G. T., Register, A., Taylor, E., and Conroy, S. Arch. Biochem. Biophys. 241, 329-336). If the labeled membranes were treated with digitonin and fractionated, the radioactivity and the plasma membrane enzyme activities coincidentally shifted to a greater density. Examination of the [3H]putrescine-labeled membranes by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography showed that the largest amount of radioactivity was associated with a large molecular weight material that did not enter the acrylamide gel. Pulse-chase experiments indicated that the large aggregate already was present in the native membrane, or that it was formed very rapidly during the putrescine incubation. The complex did not result from putrescine cross-linking between proteins since dansylcadaverine and [3H]histamine were also selectively incorporated into it. These data show that there are protein substrates in the plasma membrane which are accessible to the membrane-associated transglutaminase and that the substrates form a large molecular weight aggregate which is not dissociated by sodium dodecyl sulfate and disulfide reducing agents.
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PMID:Subcellular location and identification of a large molecular weight substrate for the liver plasma membrane transglutaminase. 286 32

Myometrial plasma membrane (MPM) preparations from rats treated with oestradiol were obtained by discontinuous sucrose-gradient centrifugation. The preparations contained calcium-stimulated and magnesium-dependent ATPase (Ca2+/Mg2+-ATPase). A dramatic decrease in the activity of Ca2+/Mg2+-ATPase was observed when preparations were treated with 0.025-10 mumol prostaglandins E2 and F2 alpha (PGE2 and PGF2 alpha)/l. In contrast, there was a marked increase in MPM-bound 5'-nucleotidase activity at low concentrations (up to 2 mumol/l) of PGE2 and PGF2 alpha; higher concentrations (up to 10 mumol/l), however, led to a progressive inhibition of enzyme activity. Association (specific and non-specific binding) of PGE2 and PGF2 alpha with MPM at pH 7 was found to require Ca2+ (half-maximal concentration approximately 0.7 mmol/l). Changes in the allosteric properties of MPM-bound 5'-nucleotidase by concanavalin A (as reflected by changes in the Hill coefficient) indicated a fluidization of the membrane induced by PGE2 and PGF2 alpha. The steady-state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene-labelled MPM decreased in PGE2- and PGF2 alpha-treated MPM from 1.24 +/- 0.04 (S.D.) to 0.66 +/- 0.01 and 0.74 +/- 0.01 respectively, which is consistent with a general increase in membrane fluidity. It is suggested that PGE2 and PGF2 alpha promote changes in the physical properties of MPM which may be relevant to the induction of uterine contractions by enzymatic regulation of intracellular calcium concentrations.
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PMID:Effect of prostaglandins E2 and F2 alpha on membrane calcium binding, Ca2+/Mg2+-ATPase activity and membrane fluidity in rat myometrial plasma membranes. 294 78


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