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)

Complete replacement of the nucleotide on the exchangeable binding site of purified calf brain tubulin by the non-hydrolyzable GTP-analogue guanylyl-(beta,gamma-methylene)diphosphonate (GMPPCP) has been achieved by treatment of tubulin-GDP with phosphodiesterase-free alkaline phosphatase. GMPPCP binds to tubulin with a low affinity relative to GTP or GDP. Binding of the analogue is linked to magnesium ion concentration and, like the binding of other guanine nucleotides, is promoted by high concentrations of glycerol. The complex of pure tubulin and GMPPCP readily assembles at 37 degrees C into microtubules or curled ribbons of protofilaments, depending on buffer composition. Assemblies are cold-reversible at 0-2 degrees C, and multiple reversible assemblies can be observed during repeated heating/cooling cycles.
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PMID:Interactions of tubulin with guanylyl-(beta-gamma-methylene)diphosphonate. Formation and assembly of a stoichiometric complex. 233 45

Rat calvaria osteoblasts derived from 21-day-old fetal rat pups undergo a temporal expression of markers of the osteoblast phenotype during a 5 week culture period. Alkaline phosphatase and osteocalcin are sequentially expressed in relation to collagen accumulation and mineralization. This pattern of expression of these osteoblast parameters in cultured rat osteoblasts (ROB) is analogous to that seen in vivo in developing fetal rat calvaria tissue (Yoon et. al: Biochem. Biophis. Res. Commun. 148:1129, 1987) and is similar to that observed in cultures of subcultivated 16-day-old embryonic chick calvaria-derived osteoblasts (COB) (Gerstenfeld, et.al: Dev. Biol. 122:46, 1987). While the cellular organization of subcultivated COB and primary ROB cultures are somewhat different, the temporal expression of the parameters remains. Both the rat and chick culture systems support formation of matrix mineralization even in the absence of beta-glycerol-phosphate. A systematic examination of factors which constitute conditions supporting complete expression of the osteoblast phenotype in ROB cultures indicate requirements for specific serum lots, ascorbic acid and the ordered deposition of mineral in the extracellular matrix. The present studies suggest that formation of a collagenous matrix, dependent on ascorbic acid, is requisite for expression of the osteoblast phenotype. In ROB cultures, expression of osteocalcin synthesis occurs subsequent to initiation of alkaline phosphatase activity and accompanies the formation of mineralized nodules. Thus, extracellular matrix mineralization (deposition of hydroxyapatite) is required for complete development of the osteoblast phenotype, as reflected by a 200-fold increase in osteocalcin synthesis. These data show the temporal expression of the various osteoblast parameters during the formation and mineralization of an extracellular matrix can provide markers reflective of various stages of osteoblast differentiation/maturation in vitro.
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PMID:Factors that promote progressive development of the osteoblast phenotype in cultured fetal rat calvaria cells. 233 47

Kinetic studies of the histochemical and histoenzymatic behavior of rabbit pancreatic parenchymas were performed 5, 30 and 90 days after Wirsung duct ligation. In control pancreas, some enzyme activities (EA) were more prominent in Langerhans islets [glucose-6-phosphatase, glucose-6-phosphate dehydrogenase (DH), isocitrate DH, glycerol-3-phosphate DH, NADPH DH], others were strongly marked in acini and ducts (alkaline phosphatase, beta-glucuronidase, acid esterase aryl-sulfatase). Histochemical and enzyme abnormalities observed in experimental rabbits reflect the post-ligation degenerative and reactive processes in both exocrine and endocrine pancreas: (1) the decrease in Krebs cycle and pentose pathway linked EA and the increased lysosomal and acid phosphatase EA reflect early (day 5) degeneration and necrosis of islets and acini (day 30); (2) proliferative processes in developed ductal epithelia are shown by an increase in both glycolytic and lysosomal EA (days 30 and 90); (3) connective tissue neogenesis and interstitial fibrosis occurred as shown by activated beta-glucuronidase, aryl-sulfatase, alkaline phosphatase and increased ribonucleoproteins and glycoaminoglycans contents (day 30); (4) on day 90, the neoformed cell clusters presenting glucose-6-phosphatase positivity (B-cell marker) are seen in the pancreas remnant. At the same time, blood insulin level increases correlated with a decrease of hyperglycemia.
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PMID:Cell features in pancreas of prediabetic and diabetic rabbits after Wirsung duct ligation. Histochemical and histoenzymatic studies. 233 24

Decay-accelerating factor (DAF) is an integral membrane protein that inhibits amplification of the complement cascade on the cell surface. We and other investigators have shown that DAF is part of a newly characterized family of proteins that are anchored to the cell membrane by phosphatidylinositol (PI). The group includes the variant surface glycoprotein (VSG) of African trypanosomes, the p63 protein of Leishmania, acetylcholinesterase (AChE), alkaline phosphatase, Thy-1, 5'-nucleotidase, and RT6.2--an alloantigen from rat T cells. The structure of the membrane anchor has been best characterized for VSG, but chemical studies of the membrane anchors of AChE and Thy-1 suggest that similar glycolipid moieties anchor these proteins to the cell surface. In the VSG, the membrane anchor consists of an ethanolamine linked covalently to an oligosaccharide and glucosamine; the entire complex is anchored to the cell membrane by PI. Immunologically, this glycolipid defines an epitope, the cross-reacting determinant (CRD), that is only revealed after removal of the diacyl glycerol anchor by a phospholipase C. By Western blotting, we show here that DAF-S (DAF released from the membrane by PI-specific phospholipase C [PIPLC]) also contains CRD. Using a newly developed immunoradiometric assay (IRMA) in which the solid-phase capturing antibody is a monoclonal antibody to DAF and the second antibody is anti-CRD, we have been able to quantitate DAF-S. By IRMA, we show that the reaction between anti-CRD and DAF-S is specific, since the binding is competitively inhibited only by the soluble form of the VSG. These observations further support the concept that the glycolipid anchors of this new family of proteins have similar structures. DAF is also found as a soluble protein in various tissue fluids as well as in Hela cell supernatants. No evidence for the presence of the CRD epitope was found on these proteins, suggesting that these forms of DAF are not released from the surface of cells by endogenous phospholipases.
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PMID:Decay-accelerating factor (DAF) shares a common carbohydrate determinant with the variant surface glycoprotein (VSG) of the African Trypanosoma brucei. 243 27

The amount and composition of lysophosphatidate present in different rat tissues have been estimated by an internal standard method in which a synthetic unnatural isomer (1-heptadecanoyl-rac-glycerol-3-phosphate) was added to the total lipid extracts, and the fatty acid composition of purified lysophosphatidate was determined. Lipids from tissues were extracted under acidic conditions, and the lysophosphatidate was purified by solvent partitions followed by thin-layer chromatography in multiple solvent systems. The purified lipid was shown to be 1-acyl-sn-glycerol-3-phosphate by chromatographic and chemical analysis, by its resistance to hydrolysis when treated with phospholipase A2 and also by its complete conversion to 1-acyl-sn-glycerol when treated with alkaline phosphatase. The fatty acid constituents of this lipid were determined by gas-liquid chromatography of the derived methyl esters. The concentrations (nmol/g of tissue) of lysophosphatidate in various tissues were: 86.2 +/- 4.2 in brain, 60.3 +/- 6.3 in liver, 46.4 +/- 6.5 in kidney, 30.6 +/- 5.0 in testis, 22.3 in heart and 19.3 in lung. Mostly (80%) saturated fatty acids were found to be present in this lyso lipid. A significantly high level of stearic acid was present in this lipid from all the tissues (50-60% in liver, kidney, brain and testis, and about 40% in heart and lung) compared to palmitic acid (10-15% in liver, kidney and brain and 25-30% in testis, heart and lung). The fatty acid compositions of phosphatidic acid, the putative product of lysophosphatidate acylation, from different tissues were also determined and palmitate was found to be the major saturated fatty acid.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Quantification, characterization and fatty acid composition of lysophosphatidic acid in different rat tissues. 275 10

Proximal tubule cells were isolated from swine kidney and cultured for periods of more than 30 days. The cells formed confluent monolayers after plating on a collagen surface and they were passaged more than 5 times on this matrix. The cells maintain several metabolic functions of proximal tubule cells, including gluconeogenesis and the ability to respond to epinephrine and parathyroid hormone. Gluconeogenesis, a principal metabolic pathway in proximal tubule cells, was examined as a function of days in culture. The isolated cells showed a nearly constant rate of gluconeogenesis from 14C-lactate, 14C-alanine and 14C-glycerol with no significant loss of activity for at least 30 days in culture. Likewise, the activities of several cytosolic and membrane associated enzymes including, alkaline phosphatase, delta-glutamyltransferase, fructose-1,6-bisphosphatase and phosphofructokinase were nearly constant over the same time period. The cells responded to treatment with epinephrine and parathyroid hormone, and the rate of gluconeogenesis from 14C-lactate doubled in the presence of these hormones. The morphological and biochemical evidence obtained in these studies show that the proximal tubule cells isolated from swine kidney provide an excellent well defined system for studying the hormonal regulation of carbohydrate metabolism in this tissue.
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PMID:Regulation of gluconeogenesis in swine kidney proximal tubule cells. 277 Jul 16

The transposon TnphoA can be used specifically to detect bacterial genes that code for cell envelope proteins. We have used TnphoA to search for genes regulated by osmolarity in Escherichia coli. Among approximately 30,000 random insertions of TnphoA into the chromosome, we have found 700 independent fusions that produce hybrid proteins with alkaline phosphatase activity. Of these, 37 were induced after growth in a medium of high osmolarity and none was repressed. Osmo-inducible fusions of phoA were found to ompC and to a gene that is probably proU. These two genes were already known to be transcriptionally induced by osmolarity. In addition, eight other genes, designated osm, were identified and mapped on the bacterial chromosome. The expression of these genes is induced by solutes that are unable to decrease the turgor pressure applied to the envelope. One of the osm genes, osmI, is also specifically induced by glycerol, which does diffuse across the cytoplasmic membrane. The expression and osmoregulation of all the osm genes were shown to occur independently of ompR and envZ, which control the expression and osmoregulation of the ompC and ompF genes in E. coli.
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PMID:The use of transposon TnphoA to detect genes for cell envelope proteins subject to a common regulatory stimulus. Analysis of osmotically regulated genes in Escherichia coli. 282 Dec 74

Fructose-2,6-bisphosphatase was purified from yeast and separated from 6-phosphofructo-2-kinase and alkaline phosphatase. The enzyme released Pi from the 2-position of fructose 2,6-bisphosphate and formed fructose 6-phosphate in stoichiometric amounts. The enzyme displays hyperbolic kinetics towards fructose 2,6-bisphosphate, with a Km value of 0.3 microM. It is strongly inhibited by fructose 6-phosphate. The inhibition is counteracted by L-glycerol 3-phosphate. Phosphorylation of the enzyme by cyclic-AMP-dependent protein kinase causes inactivation, which is reversible by the action of protein phosphatase 2A.
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PMID:Fructose-2,6-bisphosphatase and 6-phosphofructo-2-kinase are separable in yeast. 282 52

1-Alkyl-2-acetyl-sn-glycerol (alkylacetyl-G) is an important intermediate in the biosynthesis of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine (platelet-activating factor) from 1-alkyl-2-lyso-sn-glycero-3-phosphate (alkyllyso-GP) via the de novo pathway. In the present investigation, we have characterized a 1-alkyl-2-acetyl-sn-glycero-3-phosphate (alkylacetyl-GP) phosphohydrolase in rat spleens that catalyzes the conversion of alkylacetyl-GP to alkylacetyl-G. The bulk of the enzymatic activity (53%) is located in the microsomal fraction, whereas 28% of the activity is present in mitochondria. The microsomal enzyme has an optimal pH of 7.0-7.4, an "apparent" Km of 31.8 microM for alkylacetyl-GP, and is widely distributed in various rat tissues. Studies of alkylacetyl-GP phosphohydrolase with respect to substrate specificity, pH profiles, sensitivities to temperature, and effects of detergent, ethanol, or cations indicate the activity of this enzyme can be distinguished from the activities of a nonspecific phosphomonoesterase or phosphatidate phosphohydrolase. Like alkyllyso-GP:acetyl-CoA acetyltransferase, the alkylacetyl-GP phosphohydrolase shows no notable substrate selectivities with regard to variations in alkyl chain length (C16:0 versus C18:0) at the sn-1 position or short chain acyl groups (C2:0 to C6:0, with the exception of C3:0) at the sn-2 position of the glycerol moiety. The enzymatic activity of alkylacetyl-GP phosphohydrolase is 30-90-fold higher than alkyllyso-GP:acetyl-CoA acetyltransferase in most tissues examined. Even though alkyllyso-GP is a substrate for alkyllyso-GP:acetyl-CoA acetyltransferase, it can also be degraded by alkylacetyl-GP phosphohydrolase. Thus, our findings coupled with earlier results imply that specificities of the molecular species of platelet-activating factor synthesized de novo are determined by the enzyme involved in the final step of this pathway, the dithiothreitol-insensitive alkylacetyl-G:CDP-choline cholinephosphotransferase. Furthermore, alkyl-lyso-GP:acetyl-CoA acetyltransferase appears to be the rate-limiting step in the de novo synthesis of alkylacetyl-G.
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PMID:Formation of 1-alkyl-2-acetyl-sn-glycerols via the de novo biosynthetic pathway for platelet-activating factor. Characterization of 1-alkyl-2-acetyl-sn-glycero-3-phosphate phosphohydrolase in rat spleens. 282 51

H+-translocating, Mg2+-ATPase was solubilized from vacuolar membranes of Saccharomyces cerevisiae with the zwitterionic detergent N-tetradecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate and purified by glycerol density gradient centrifugation. Partially purified vacuolar membrane H+-ATPase, which had a specific activity of 18 units/mg of protein, was separated almost completely from acid phosphatase and alkaline phosphatase. The purified enzyme required phospholipids for maximal activity and hydrolyzed ATP, GTP, UTP, and CTP, with this order of preference. Its Km value for Mg2+-ATP was determined to be 0.21 mM and its optimal pH was 6.9. ADP inhibited the enzyme activity competitively, with a Ki value of 0.31 mM. The activity of purified ATPase was strongly inhibited by N,N'-dicyclohexylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, tributyltin, 7-chloro-4-nitrobenzoxazole, diethylstilbestrol, and quercetin, but was not affected by oligomycin, sodium azide, sodium vanadate, or miconazole. It was not inhibited at all by antiserum against mitochondrial F1-ATPase or mitochondrial F1-ATPase inhibitor protein. These results indicated that vacuolar membrane H+-ATPase is different from either yeast plasma membrane H+-ATPase or mitochondrial F1-ATPase. The vacuolar membrane H+-ATPase was found to be composed of two major polypeptides a and b of Mr = 89,000 and 64,000, respectively, and a N,N'-dicyclohexylcarbodiimide binding polypeptide c of Mr = 19,500, whose polypeptide composition was also different from those of either plasma membrane H+-ATPase or mitochondrial F1-ATPase of S. cerevisiae.
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PMID:Purification and properties of H+-translocating, Mg2+-adenosine triphosphatase from vacuolar membranes of Saccharomyces cerevisiae. 285 69


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