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:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Characteristics of 5'-nucleotide phosphodiesterase (phosphodiesterase I, EC 3.1.4.1) and alkaline phosphatase (EC 3.1.3.1) activities in tumor cell lines of human and murine origin were examined. Of the 15 cell lines tested, 5'-nucleotide phosphodiesterase activity in 13 cell lines and alkaline phosphatase activity in 10 cell lines were inhibited by N-ethylmaleimide and activated by dithiothreitol (N-ethylmaleimide-sensitive), and suggested to be SH-enzymes. In contrast, the two phosphohydrolases from normal tissues were inactivated by dithiothreitol, but not by N-ethylmaleimide (dithiothreitol-sensitive). There was only one tumor cell line in which both activities were dithiothreitol-sensitive. Human hepatoma PLC/PRF/5 cells appear to possess both types of 5'-nucleotide phosphodiesterase and alkaline phosphatase, and the subcellular distribution of these enzymes in this cell line was investigated. Dithiothreitol-sensitive 5'-nucleotide phosphodiesterase and alkaline phosphatase of PLC/PRF/5 cells were localized in the plasma membrane as in normal tissues, but N-ethylmaleimide-sensitive phosphohydrolases were soluble cytosolic proteins. N-Ethylmaleimide-sensitive 5'-nucleotide phosphodiesterase and alkaline phosphatase activities from other cell lines were also recovered in the cytosol. Molecular masses of cytosolic N-ethylmaleimide-sensitive phosphohydrolases were apparently smaller than their membrane-bound dithiothreitol-sensitive counterparts, as judged from gel filtration. It was concluded that many tumor cell lines lack plasma membrane 5'-nucleotide phosphodiesterase and alkaline phosphatase, but express enzymes with similar activities in the cytosol, with properties clearly distinguishable from enzymes so far characterized.
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PMID:5'-Nucleotide phosphodiesterase and alkaline phosphatase in tumor cells: evidence for existence of novel species in the cytosol. 283 40

Synthetic peptide 1142-1153 of the insulin receptor was phosphorylated on tyrosine by the insulin receptor and found to be a potent substrate for dephosphorylation by rat liver particulate and soluble phosphotyrosyl protein phosphatases. Apparent Km values were approximately 5 microM. Vm values (nmol phosphate removed/min per mg protein) were 0.62 (particulate) and 0.2 (soluble). This corresponds to 80% of total activity being membrane-associated, indicating that membrane-bound phosphatases are important receptor phosphatases. The phosphatase activities were distinct from acid and alkaline phosphatase. In conclusion peptide 1142-1153 provides a useful tool for the further study and characterization of phosphotyrosyl protein phosphatases.
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PMID:Assay of phosphotyrosyl protein phosphatase using synthetic peptide 1142-1153 of the insulin receptor. 284 84

When membrane-bound human liver alkaline phosphatase was treated with a phosphatidylinositol (PI) phospholipase C obtained from Bacillus cereus, or with the proteases ficin and bromelain, the enzyme released was dimeric. Butanol extraction of the plasma membranes at pH 7.6 yielded a water-soluble, aggregated form that PI phospholipase C could also convert to dimers. When the membrane-bound enzyme was solubilized with a non-ionic detergent (Nonidet P-40), it had the Mr of a tetramer; this, too, was convertible to dimers with PI phospholipase C or a protease. Butanol extraction of whole liver tissue at pH 6.6 and subsequent purification yielded a dimeric enzyme on electrophoresis under nondenaturing conditions, whereas butanol extraction at pH values of 7.6 or above and subsequent purification by immunoaffinity chromatography yielded an enzyme with a native Mr twice that of the dimeric form. This high molecular weight form showed a single Coomassie-stained band (Mr = 83,000) on electrophoresis under denaturing conditions in sodium dodecyl sulfate, as did its PI phospholipase C cleaved product; this Mr was the same as that obtained with the enzyme purified from whole liver using butanol extraction at pH 6.6. These results are highly suggestive of the presence of a butanol-activated endogenous enzyme activity (possibly a phospholipase) that is optimally active at an acidic pH. Inhibition of this activity by maintaining an alkaline pH during extraction and purification results in a tetrameric enzyme. Alkaline phosphatase, whether released by phosphatidylinositol (PI) phospholipase C or protease treatment of intact plasma membranes, or purified in a dimeric form, would not adsorb to a hydrophobic medium. PI phospholipase C treatment of alkaline phosphatase solubilized from plasma membranes by either detergent or butanol at pH 7.6 yielded a dimeric enzyme that did not absorb to the hydrophobic medium, whereas the untreated preparations did. This adsorbed activity was readily released by detergent. Likewise, alkaline phosphatase solubilized from plasma membranes by butanol extraction at pH 7.6 would incorporate into phosphatidylcholine liposomes, whereas the enzyme released from the membranes by PI phospholipase C would not incorporate. The dimeric enzyme purified from a butanol extract of whole liver tissue carried out at pH 6.6 did not incorporate. We conclude that PI phospholipase C converts a hydrophobic tetramer of alkaline phosphatase into hydrophilic dimers through removal of the 1,2-diacylglycerol moiety of phosphatidylinositol. Based on these and others' findings, we devised a model of alkaline phosphatase's conversion into its various forms.
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PMID:The solubilization of tetrameric alkaline phosphatase from human liver and its conversion into various forms by phosphatidylinositol phospholipase C or proteolysis. 284 68

Soluble and membrane-bound phosphatase and phosphodiesterase activities are present in preparations of 1,3-beta-D-glucan synthase from pea epicotyls. UDP-glucose phosphodiesterase and non-specific alkaline phosphatase could be partially inhibited by N-ethylmaleimide or iodoacetamide and partially removed from membranes by washing. Such treatments helped to prolong 1,3-beta-glucan synthase activity. Nevertheless, the 1,3-beta-D-glucan synthase activity in washed membranes still gradually decreased during incubation in buffer at 30 degrees C. The rate of decay was reduced by adding more specific phosphatase inhibitors, e.g. molybdate, vanadate or fluoride, or by addition of nucleotides, and much of the loss of 1,3-beta-D-glucan synthase activity during preincubation could be restored by addition of phosphatidylethanolamine to the assay mixtures. It is concluded that membrane phospholipid is an essential part of the environment of 1,3-beta-glucan synthase and must be maintained intact in order for the enzyme to remain fully active.
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PMID:Phosphatases and phosphodiesterases interfere with 1,3-beta-D-glucan synthase activity in pea epicotyl membrane preparations. 284 92

Membrane and cytosolic factors cooperate to generate NADPH-oxidase. The study of the syndrome of NADPH-oxidase deficiencies, chronic granulomatous disease, has enabled the identification of two membrane factors: a flavin adenine dinucleotide flavoprotein and a b cytochrome. The nature of the cytosolic components is still unknown, but a 47-kD protein, whose phosphorylation occurs in parallel with the generation of a respiratory burst in intact cells, seems to be one of the cytosolic factors. The subcellular localization of the membrane-bound NADPH-oxidase components has been studied in neutrophils: In unstimulated cells, only a minute fraction of the NADPH-oxidase components is localized in the plasma membrane, whereas approximately 80% is localized in the membrane of the specific granules and the majority of the rest is in a newly described membrane-bound compartment, the secretory granules, identified by latent alkaline phosphatase. During stimulation, these NADPH-oxidase components are translocated to the plasma membrane as a result of fusion of granule membrane with plasma membrane. Only the NADPH-oxidase components present in the plasma membrane are incorporated in the respiratory burst oxidase generated in intact cells.
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PMID:Subcellular localization and dynamics of components of the respiratory burst oxidase. 285 26

The activities of monoamine oxidase (MAO), catechol-O-methyltransferase (COMT), phenol sulfotransferase (PST), alkaline phosphatase (AP), gamma-glutamyl transpeptidase (GT), and angiotensin converting enzyme (ACE) were quantitated in primary cultures of bovine brain microvessel endothelial cell monolayers and cerebral gray matter. Significant MAO-A and -B, cytosolic and membrane-bound COMT, PST, AP, GT, and ACE activities are demonstrated in bovine gray matter. By comparison, enzyme activities of the monolayers vary with the age of the monolayer and are generally higher in complete monolayers. Relative to gray matter enzyme activities, the monolayers are enriched with AP, GT, and ACE, enzymes considered to be markers for brain endothelium. Results also indicate that the activities of MAO-A and PST in the monolayers approach those found in the gray matter. Conversely, cytosolic COMT and MAO-B activities in the monolayers are negligible and much lower, respectively, compared to activities in gray matter. Additional studies with both tissues suggest that the PST of both tissues is the thermostable form of the enzyme.
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PMID:Catecholamine-metabolizing enzymes of bovine brain microvessel endothelial cell monolayers. 287 Nov 35

To study the acute effect of ethanol on various constituents of the bile, female Wistar rats received by intravenous administration 0.9% NaCl solution either alone or containing in addition ethanol (0.1 ml ethanol 96% hr-1 100 g body weight-1). Compared to saline-treated controls there was a significant enhancement of biliary gamma-glutamyltransferase excretion after ethanol infusion for 5 hr by 166% (22.1 +/- 2.8 microU/min/100 g body weight vs. 58.2 +/- 13.7; P less than 0.0125), whereas no changes or only marginal alterations have been observed for bile flow and the biliary excretion of total bile acids and alkaline phosphatase. The selective enhancement of biliary gamma-glutamyltransferase excretion by ethanol can be ascribed to an increased solubilization of the membrane-bound enzyme originating from the bile canaliculi of the hepatocytes and/or the epithelial cells of the bile ducts. Since the biliary excretion of total bile acids remained unchanged by ethanol, the observed selective solubilization of gamma-glutamyltransferase may occur by a mechanism primarily not involving total bile acids and could be linked to a direct effect of ethanol on physico-chemical properties such as an increased fluidity of liver plasma membranes.
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PMID:Biliary excretion of gamma-glutamyltransferase. Selective enhancement by acute ethanol administration. 287 9

For the investigation of the possibility of its being a marker enzyme for tumor cells, the activity of dipeptidyl peptidase (DPP) IV (EC 3.4.14.5), a membrane-bound enzyme, in cultured human carcinoma cells was examined. The homogenates of three carcinoma cell lines (HeLa, KB, and K-44) contained lower glycylprolyl methylcoumarinamide (Gly-Pro-MCA) hydrolase activities at pH 8.7 (assumed to be DPP IV) and higher activities of alkaline phosphatase and gamma-glutamyl transpeptidase, which are also membrane-bound enzymes, than those of normal human fibroblasts (HF). Examination of carcinoma cells for the subcellular localization and pH optimum of Gly-Pro-MCA hydrolase activity revealed that the activity of a lysosomal enzyme that hydrolyzes Gly-Pro-MCA at pH 6.4 was markedly increased in carcinoma cells, but not in normal cells. The separation and characterization of Gly-Pro-MCA hydrolases by gel filtration, affinity chromatography, and substrate specificity demonstrated that HF have three peaks indicating DPP IV, DPP II, and an unknown enzyme, whereas the three carcinoma cell lines gave a prominent peak indicating DPP II and a trace of DPP IV. The DPP II activity was 6- to 24-fold higher in carcinoma cell lines than in HF, and it also was 2.85- to 4.13-fold higher than the DPP IV activity in carcinoma cell lines but was 10-fold lower in HF. These clear enzymatic differences between carcinoma cells and normal HF may be useful as a marker of malignancy.
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PMID:Alteration in dipeptidyl peptidase activities in cultured human carcinoma cells. 288 39

Cell fractionation studies have been performed, in order to obtain insight into the subcellular distribution of Dictyostelium adenylate cyclase and guanylate cyclase and also to provide a starting point for further study and isolation of these enzymes and their regulatory components. Adenylate cyclase and cAMP receptors were found in the same membrane fractions, but were distributed different from the plasma membrane marker alkaline phosphatase. Guanylate cyclase was partially soluble, partially particulate. In isopycnic gradients, particulate guanylate cyclase was present in other fractions than cAMP receptors and adenylate cyclase, but in similar ones to alkaline phosphatase. These observations are consistent with the hypothesis that cell-surface cAMP receptors and adenylate cyclase interact via a membrane-bound G-protein, whereas the receptors activate guanylate cyclase via a cytosolic factor. The adenylate cyclase activity in membranes obtained by sucrose gradient centrifugation was retained in the presence of various detergents, while with the same detergents the activity of particulate guanylate cyclase was lost. This adenylate cyclase was solubilized as assessed by gel filtration and centrifugation experiments, and it behaved heterogeneous in fractionation studies. In gel filtration, the major component eluted at a position corresponding to a Stokes radius of 4-7 nm. A purification of about 70-fold as compared to the cell homogenate was obtained by affinity chromatography of adenylate cyclase on ATP-Sepharose. We conclude that cell fractionation provides useful starting material for isolation and further study of Dictyostelium adenylate cyclase.
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PMID:Cell fractionation, detergent sensitivity and solubilization of Dictyostelium adenylate cyclase and guanylate cyclase. 288 13

Sodium butyrate and dimethylsulfoxide (DMSO), two known chemical inducers of cell differentiation, were examined on MCF-7 breast cancer cells. Both agents reduce the proliferative capacity of MCF-7 cells, as reflected by inhibition of colony formation in semisolid agar. Sodium butyrate is shown to enhance markedly the activity of two plasma membrane-bound enzymes, alkaline phosphatase and gamma-glutamyl transpeptidase. DMSO does not enhance the activity of these enzymes, but rather induces a small decrease in gamma-glutamyl transpeptidase activity. The present results show that although both agents inhibit cell proliferation, they have a distinct effect on phenotypic expression.
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PMID:Differential effects of sodium butyrate and dimethylsulfoxide on gamma-glutamyl transpeptidase and alkaline phosphatase activities in MCF-7 breast cancer cells. 289 May 41


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