Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A procedure for the isolation of plasma membranes from protoplasts of suspension-cultured soybean is described. Protoplasts were prepared by enzymic digestion of the cell wall and the plasma membrane was labelled with radioactive diazotized sulphanilic acid. The membrane systems from broken protoplasts were separated by continuous isopycnic sucrose gradient centrifugation. Radioactivity was localized in a band possessing a buoyant density of 1-14 g ml-1. The activities of NADPH- and NADH-cytochrome c reductase, fumarase, Mg2+-ATPase, IDPase and acid phosphodiesterase in the various regions of the density gradient were determined. A plasma membrane fraction was selected which was relatively uncontaminated with membranes derived from endoplasmic reticulum, tonoplasts and mitochondria. The results indicated that Mg2+-ATPase and possibly acid phosphodiesterase were associated with the plasma membrane.
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PMID:The isolation of plasma membrane from protoplasts of soybean suspension cultures. 56 Oct 89

The dermal cells in grey, xanthic, and white goldfish integuments were cytochemically characterized for the following enzymatic activities: tyrosinase, DOPA-oxidase, cytochrome oxidase, monoamine oxidase, peroxidase, non-specific esterase, cholinesterase, NAD-diaphorase, NADP-diaphorase, aryl sulfatase, nucleotide phosphodiesterase, beta-glucuronidase, acid phosphatase, alkaline phosphatase, adenosine triphosphatase, thiamine pyrophosphatase, glucose-6-phosphatase, aldolase, as well as succinate, malate, isocitrate, glutamate, glucose-6-phosphate, 6-phosphogluconate, alpha-glycerophosphate, alcohol, lactate, and beta-hydroxybutyrate dehydrogenases. It was found that the epidermis was a significant barrier to the access of cytochemical reaction substrates. Removal of the epidermal barrier provided dermal cell localizations of enzymatic activities which were reproducible. Further, alterations in reaction times and temperatures from the mammalian methodology provided conditions fe various integumental cells were compared for possible interrelationships. The basic foundations for future work with the dermis of poikilothermic vertebrates on an experimental basis were established. In addition, a previously undescribed non-pigmented dermal cell, the "x"-cell, was found to have enzymatic characteristics similar to both melanophores and lipophores. The "x"-cell may be the common precursor of both types of pigment cells.
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PMID:Cytochemical characterization of goldfish (Carassius auratus L.) dermis with special reference to the pigment cells. 82 86

An enzymatic cycling procedure for beta-NADP+ generated by the enzyme 3'-phosphodiesterase, 2':3'-cyclic nucleotide (EC 3.1.4.37) from its substrate 2':3'-cyclic NADP+ is described. The enzymes glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and diaphorase (EC 1.8.1.4) are used to cycle the cofactor between its oxidized and reduced forms in the presence of glucose-6-phosphate and p-iodonitrotetrazolium violet (INT) with the concomitant production of colored INT-formazan, monitored at 492 nm. The amplification is about 400-fold per hour and is sensitive enough to detect 6 x 10(-13) mol of NADP(H). A simple procedure for the optimization of this cycling assay is also described. Conjugates to 3'-phosphodiesterase, 2':3'-cyclic nucleotide may be used in heterogeneous enzyme immunoassays for the detection of small quantities of haptens or proteins in biological fluids.
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PMID:An enzymatic cycling procedure for beta-NADP+ generated by 3'-phosphodiesterase, 2':3'-cyclic nucleotide. 132 Mar 51

Previous studies of embryonic rat skeletal muscle cultures suggested that there was a correlation between intracellular adenosine 3',5'-cyclic monophosphate (cAMP) concentration and activities of enzymes of oxidative energy metabolism. We investigated the ability of agents that elevate intracellular cAMP by three different mechanisms (activation of adenylate cyclase, inhibition of phosphodiesterase, and analogues) to alter not only the activities of 11 glycolytic and mitochondrial enzymes but also the rate of flux through aerobic glucose oxidation in intact myotubes derived from regenerating rat muscle satellite cells. The enzyme activities were not consistently altered when cAMP was elevated, with the exception of the electron transport enzyme, NADH cytochrome c reductase, whose activity was elevated by exposure of the myotubes to cholera toxin (110% of control), 3-isobutyl-1-methylxanthine (112%), caffeine (119%), and 8-bromoadenosine 3',5'-cyclic monophosphate (120%). The rate of flux of aerobic glucose oxidation was elevated by all agents (116-157% of control) except cholera toxin. This study allowed us to compare the metabolic characteristics of myotube cultures derived from satellite cells with those from embryonic muscle, from a previous study. Despite differences between these two models, together, the data present strong evidence that an increase in intracellular cAMP can cause an increase in oxidative capacity.
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PMID:Increased aerobic glucose oxidation by cAMP in cultured regenerated skeletal myotubes. 242 46

The distribution of [3H]leukotriene D4 [( 3H]LTD4) receptors in subcellular membrane fractions obtained from sheep tracheal smooth muscle was studied. Using differential centrifugation and discontinuous sucrose density gradient centrifugation, the subcellular membranes were separated into six fractions. The [3H]LTD4 receptor distribution profile in these fractions correlated with markers for the plasma membrane (5'-nucleotidase and alkaline phosphodiesterase) and did not correlate with markers for the mitochondria (cytochrome c oxidase and succinate-dependent cytochrome c reductase). The dissociation constant (Kd) and maximum number of binding sites (Bmax) for [3H]LTD4 binding to the receptors in the crude mixture of membranes (PII) were 0.38 +/- 0.2 nM and 77 +/- 14 fmol/mg of protein, respectively. The Kd and Bmax of [3H]LTD4 binding to the receptors in the plasma membrane-enriched fraction (FII) were 0.40 +/- 0.2 nM and 268 +/- 46 fmol/mg of protein, respectively. The specificity profile of the [3H]LTD4 receptors in the plasma membrane-enriched fraction was equivalent to that observed in the crude membrane and correlated with the agonist myotonic activities in the smooth muscle contraction assay system. Furthermore, the binding of [3H]LTD4 to the plasma membrane receptors was modulated by guanine nucleotides in a manner analogous to that observed in crude membranes, suggesting that agonist interaction with the receptors was regulated by guanine nucleotide binding protein. These results suggest that, in sheep tracheal smooth muscle, the plasma membrane is the primary location of specific LTD4 receptors.
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PMID:Subcellular localization of leukotriene D4 receptors in sheep tracheal smooth muscle. 284 53

Partially purified plasma membranes were obtained from chick-embryo muscle cells grown in tissue culture. The purification procedure involved homogenization in buffered isotonic sucrose followed by differential and sucrose density gradient centrifugations. The activities of five plasma-membrane markers, as well as microsomal and mitochondrial markers, were followed throughout the purification. When cultures were labeled with [(125)I]alpha-bungarotoxin, which binds to the surface of cultured muscle cells, the distributions of bound alpha-bungarotoxin and Na(+),K(+)-ATPase (EC 3.6.1.3) activity were nearly identical. The activities of these two plasma-membrane markers were maximal in the upper two fractions of the sucrose density gradient and were purified 5- to 7-fold with respect to total particulate protein. These fractions contained 20-30% of the Na(+),K(+)-ATPase activity and bound alpha-bungarotoxin, 4% of the microsomal marker TPNH-dependent cytochrome c reductase, 0.2% of the mitochondrial marker succinate-dependent cytochrome c reductase, 2.7% of the cellular RNA, and 0.02% of the DNA. The activity of the commonly used plasma-membrane marker, 5'-nucleotidase (EC 3.1.3.5), was low in the upper two sucrose gradient fractions and was maximal in a more dense fraction. The distributions of the other two plasma-membrane markers, leucyl beta-naphthylamidase and phosphodiesterase I, were intermediate between Na(+),K(+)-ATPase and 5'-nucleotidase. The distributions of all markers were similar in preparations from cultures containing mononucleated myogenic cells, multinucleated myotubes, fibroblasts, or all three cell types. Modification of the procedure to include homogenization in the absence of sucrose resulted in a 3.4-fold purification of the membranes containing 5'-nucleotidase, which were shifted to a lower density.
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PMID:Plasma membranes from cultured muscle cells: isolation procedure and separation of putative plasma-membrane marker enzymes. 436 82

Distribution of specific binding sites for [3H]nitrendipine was studied in subcellular fractions isolated from rat gastric fundus smooth muscle and from rat myometrium. There was an excellent correlation between the distribution of [3H]nitrendipine binding determined at the nitrendipine concentrations of 0.138 and 1.38 nM, and the distribution of the plasma membrane markers K+-activated ouabain-sensitive p-nitrophenylphosphatase, 5'-nucleotidase, phosphodiesterase I, and Mg-ATPase, but not between the mitochondrial markers cytochrome c, oxidase, succinate-dependent cytochrome c reductase, or rotenone-insensitive NADH-dependent cytochrome c reductase or the putative endoplasmic reticulum marker NADPH-dependent cytochrome c reductase. The binding occurred with high affinity and with a similar (0.097-0.146 nM) equilibrium dissociation constant to all the fractions, even though the density of binding sites varied and was highest in the plasma membrane marker-enriched fractions. The maximal binding in the plasma membrane-enriched fraction from the rat gastric fundus smooth muscle was 0.43 +/- 0.04 pmol/mg, and in that from rat myometrium was 0.72 +/- 0.09 pmol/mg. Thus in the two smooth muscles studied the plasma membrane is the locus of the high affinity nitrendipine binding.
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PMID:Subcellular distribution of [3H]nitrendipine binding in smooth muscle. 632 63

Lymph node cell homogenates were fractionated by differential or isopycnic centrifugation and the fractions analyzed for biochemical markers with particular focus on plasma membrane constituents. Markers for the nucleus (DNA), mitochondria (cytochrome oxidase), and lysosomes (acid hydrolases) showed the expected distributions which were different from those of membrane-bound enzymes. 5'-Nucleotidase, alkaline phosphodiesterase, gamma-glutamyltranspeptidase, and cholesterol were membrane-bound and distributed identically after isopycnic centrifugation with peaks at 1.15. The distributions of the enzymes were all shifted to higher densities by digitonin treatment, confirming their association with plasma membrane-derived elements. The distribution of galactosyltransferase (ovalbumin acceptor), largely overlapped those of plasma membrane markers but it was only slightly shifted by digitonin, suggesting its localization in Golgi apparatus. The distribution of mannosyltransferase (dolichyl phosphate acceptor) also overlapped those of plasma membrane and Golgi markers but it was centered at higher density (1.18) and was unaffected by digitonin. It is a useful marker for endoplasmic reticulum. 50% of the activity was in low speed "nuclear" sediments where it was associated with the nuclear membrane. A number of other putative and previously used markers for the endoplasmic reticulum of lymphocytes were shown not to be localized in these membranes. In particular, NADH-cytochrome c reductase was only partly associated with the endoplasmic reticulum (56%) and the remainder of the activity was in mitochondria (44%). The results show the heterogeneity in equilibrium density of plasma membrane vesicles and the considerable overlap of their distribution with those of other cellular membranes; they should provide a basis for the more rational design of preparative procedures for the lymphocyte plasma membrane.
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PMID:Characterization of rat lymphocyte cell membranes by analytical isopycnic centrifugation. 660 29

The oxalate-stimulated and -independent components of the ATP-dependent azide insensitive Ca-uptake by rat vas deferens smooth muscle microsomes differ in the following properties: (a) 5, 5'-disulfonate stilbene (DIDS) and digitonin inhibited the oxalate-independent Ca-uptake more strongly than the oxalate-stimulated component; (b) phosphatidylserine inhibited the oxalate-stimulated Ca-uptake and had no significant effect on the oxalate-independent uptake and (c) digitonin treatment of microsomes changed the density distributions of the two modes differentially. The untreated microsomes gave two Ca-uptake peaks on sucrose density gradients: one at density 1.130 +/- 0.010 g/ml and the other at 1.214 +/- 0.005 g/ml. Digitonin treatment shifted the distribution of the lower density peak to slightly higher density for the oxalate-independent Ca-uptake but not for the oxalate-stimulated Ca-uptake. Distribution of phosphodiesterase I was also shifted to higher densities while distributions of the higher density Ca-uptake peak, NADPH: cytochrome c reductase and of cytochrome c oxidase were not significantly altered. Thus clearly the oxalate-stimulated and the oxalate-independent Ca-uptake in rat vas deferens smooth muscle microsomes show several differences but it is unknown whether the differences are due to the existence of two distinct Ca-pump proteins or due to different microenvironment of the same protein resulting from membrane heterogeneity.
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PMID:ATP-dependent Ca-uptake by rat vas deferens smooth muscle microsomes: properties of oxalate stimulated and oxalate-independent Ca-uptake. 672 23

Proximal tubules were isolated in highly pure form from rabbit cortices by a mechanical procedure that is known to preserve the structural and metabolic aspects of the tubular cells. Postnuclear supernates prepared from the isolated tubules were subjects to isopycnic centrifugation in linear sucrose gradients. The enzyme activities associated with the plasma membrane (gamma-glutamyl transpeptidase, amino-peptidase M, alkaline phosphatase, Na-K-ATPase, and phosphodiesterase I) exhibited sharp unimodal frequency-density profiles with a median density near 1.16 g/ml, which shifted to a heavier density when treated with digitonin. The lysosomal enzymes, N-acetyl-beta-glucosaminidase, alpha-mannosidase, and cathepsin B, and the peroxisomal enzyme catalase exhibited particle-associated activity near a density of 1.22 g/ml. Disruption of these particles by freezing and thawing resulted in these activities appearing in the rho = 1.10 g/ml region of the gradient where the soluble cytosolic enzyme, phosphoglucomutase, exhibited activity. Cytochrome oxidase activity typical of mitochondria gave a sharp unimodal profile at rho = 1.18 g/ml. Microsomal glucose-6-phosphatase and NADPH: cytochrome c reductase activities gave median densities near 1.16 g/ml, which did not change after incubation with digitonin. Galactosyl transferase activity gave a skewed profile at rho = 1.16 g/ml and showed a slight shift to heavier density after digitonin. This study of the enzymatic activities and density gradient distribution of the components of the proximal tubule cells provides the methodology for the further study of the cellular processing of endogenous and exogenous substances by this vital cell type.
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PMID:Analytical cell fractionation of isolated rabbit renal proximal tubules. 730 Jan 16


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