Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Insulin treatment of isolated liver plasma membranes induced the release of 5'-nucleotidase and alkaline phosphatase. This effect was maximal at physiological hormone concentrations, being 36% and 17% for 5'-nucleotidase and alkaline phosphatase respectively, and was fully mimicked by the phosphatidylinositol specific phospholipase C (PI-PLC), thus confirming the presence of a glycosylphosphatidylinositol anchoring-system for these exofacial enzymatic proteins. The complete inhibition of insulin dependent enzyme release by neomycin is strongly supportive of an involvement of membrane-located PI-PLC activity. In addition, the insulin-like effect on enzyme release induced by the GTP non-hydrolysable analog, GTP-gamma-S, and its sensitivity to the pertussis toxin are in favour of a mediatory role exerted by the G proteins system, in the transduction of some actions of insulin.
 ...
PMID:Insulin-dependent release of 5'-nucleotidase and alkaline phosphatase from liver plasma membranes. 133 52

A number of cell-surface proteins are anchored by a phosphatidylinositol (PI)-glycan moiety. These proteins can be released by PI-specific phospholipases C (PI-PLC). Decay-accelerating factor (DAF) is such a cell-surface protein that protects cells from inadvertent complement attack by binding to and inactivating C3 and C5 convertases. We have studied the regulation of DAF synthesis in human umbilical vein endothelial cells (HUVEC), a cell that has the highest level of surface DAF among those human cells that have been studied. HUVEC DAF was measured by immunoradiometric assay of detergent extracts and of cell supernatants after treatment of cells with a bacterial (Bacillus thuringiensis) PI-PLC. Eighty percent of the HUVEC DAF (4 to 8 x 10(5) molecules/cell) was released by exogenously added PI-PLC, indicating that it is predominantly PI-anchored. The level of PI-PLC-sensitive HUVEC DAF was increased three- to fourfold by overnight treatment of cultures with the protein kinase C activators, PMA (1 to 10 nM), phorbol-12,13-dibutyrate (10 to 100 nM), and teleocidin A (1 to 10 nM) under conditions where cell number, protein, and lactate dehydrogenase remain unchanged. This DAF synthesis was blocked by the protein kinase C inhibitor K-252a in a dose-dependent manner (ED50 = 0.06 microM). The biologically inactive phorbols, 4-alpha-phorbol-12 myristate-13-acetate (1 microM) and 4-alpha-phorbol-12, 13-didecanoate (1 microM) did not increase DAF levels. The newly expressed DAF in PMA-stimulated cells was still largely PI-anchored. In contrast, another PI-anchored protein, alkaline phosphatase, was not altered by PMA treatment, demonstrating that the PMA effect is not uniform among all surface proteins. The increased expression of DAF only was evident 8 h after PMA addition and was blocked by the RNA and protein synthesis inhibitors, actinomycin D and cycloheximide, indicating that both transcription and translation are required for DAF synthesis induced by phorbol esters. It is concluded that protein kinase C activators cause selective induction of endothelial cell DAF and that DAF synthesis involves protein kinase C activation.
 ...
PMID:Phorbol esters increase synthesis of decay-accelerating factor, a phosphatidylinositol-anchored surface protein, in human endothelial cells. 168 81

We have previously shown that two ectoenzymes, acetylcholinesterase (AChE) and alkaline phosphatase, are released from the surface and from particulate fractions of the parasite Schistosoma mansoni, by a phosphatidylinositol-specific phospholipase C (PtdIns-PLC) of bacterial origin. Exposure to PtdIns-PLC not only removes large amounts of AChE from the surface of intact, viable Schistosoma in culture, but is accompanied by a concomitant increase in overall levels of AChE in the parasite. The same phenomenon is observed with PtdIns-PLC from two different bacterial sources; Staphylococcus aureus and Bacillus thuringiensis. The increase in AChE levels may be ascribed to de novo synthesis since exposure to PtdIns-PLC, in the presence of the protein-synthesis inhibitor cycloheximide, totally blocked the increase in AChE activity. Furthermore, PtdIns-PLC induced an increased incorporation of [35S]methionine into the AChE immunoprecipitated by a specific anti-AChE serum. This increase is selective for AChE, since total protein synthesis remained almost unchanged after PtdIns-PLC addition, and little or no effect was observed on the enzymatic activity of alkaline phosphatase, which is also glycophosphatidylinositol anchored. Since cleavage of the phosphatidylinositol anchor by PtdIns-PLC should liberate diacylglycerol, which may act as second messenger, we investigated the effect of exogenous diacylglycerols on the synthesis of AChE in S. mansoni. Three different diacylglycerols were tested as possible inducers of AChE activity in the parasite. Both 1-oleoyl-2-acetyl-sn-glycerol and 1,2-dimyristoyl-sn-glycerol were able to increase AChE activity by 35-40% at concentrations of 25 micrograms/ml. A higher concentration of 1,2-dioctanoyl-sn-glycerol (70 micrograms/ml) was needed to produce an equivalent effect. Moreover, addition of phorbol-12-myristate-13-acetate, together with the calcium ionophore A23187, produced a similar increase in AChE activity. Finally, polymixin B, a specific inhibitor of protein kinase C, partially blocked the increase in AChE activity induced by PtdIns-PLC. Our results suggest the involvement of glycophosphatidyl membrane-anchor breakdown products as putative second messengers in the parasite S. mansoni.
 ...
PMID:Phosphatidylinositol-specific phospholipase C induces biosynthesis of acetylcholinesterase via diacylglycerol in Schistosoma mansoni. 184 73

The molecular nature and possible presence of a glycan-phosphatidylinositol anchor (GPI-anchor) in CA125 molecules was investigated. Serial lectin affinity chromatography and N- or O-glycanase treatment to reduce antigenicity showed that CA125 contained certain N- and O-glycosylated sugar chains in the molecule, like a glycoprotein. CA125 released from ovarian cancer tissues increased time-dependently following phosphatidylinositol-specific phospholipase C (PI-PLC) treatment, concomitant with the release of tissue-unspecific alkaline phosphatase. Western blotting of CA125 treated by PI-PLC showed a single band of 90 kD instead of the 162- and 76-kD bands of the native antigen. Further, ovarian cancer tissues subjected to PI-PLC treatment lost the immunohistochemical localization of CA125 with OC125 antibody. Consequently, it is strongly suggested that CA125 is a glycoprotein that has both N- and O-linked sugar chains and a membranous GPI-anchoring moiety, and further, that its 90-kD form is the antigen without the GPI-anchor.
 ...
PMID:Molecular nature and possible presence of a membranous glycan-phosphatidylinositol anchor of CA125 antigen. 196 50

One hundred eighteen patients with stage D (D1 or D2) prostate cancer with a mean age of 69 years were treated with monthly goserelin (Zoladex; ICI 118, 630; ICI Americas Inc, Wilmington, DE, property of Imperial Chemical Industries PLC) injections and the data were analyzed for predictive parameters for best response and time to treatment failure (National Prostatic Cancer Project [NPCP] and Eastern Cooperative Oncology Group [ECOG] criteria). For best response in a univariate analysis, the performance status (PS 0-1 v 2-3) (P = .01), hematocrit (P = .04), and pain (P = .04) were significant. For time to treatment failure by univariate analysis, ECOG performance status (0-1 v 2-3) was most predictive (P less than .0001), followed by pain at entry (P = .0002), initial testosterone (T) level (greater than 250 ng/dL) (P = .0005), age less than 69 years (P = .02), alkaline phosphatase (less than 115 IU/L) (P = .03), hemoglobin (less than 14 g/dL) (P = .03), whereas normal acid phosphatase (less than 3 IU/mL) (P = .29) was not predictive. In multivariate analysis for time to treatment failure, only the ECOG performance status was of significance (P = .01). Estimated median time to treatment failure for PS of 0-1 was 88 weeks and for PS of 2-3 was 31 weeks.
 ...
PMID:Predictive initial parameters for response of stage D prostate cancer to treatment with the luteinizing hormone-releasing hormone agonist goserelin. 213 2

We explored the biochemical basis for the disorder pseudohypophosphatasia (PsHYPT) in one patient by examining the substrate specificity and localization of alkaline phosphatase (ALP) in cultured dermal fibroblasts. Despite substantial ALP activity, in cell homogenates, toward the artificial substrate 4-methyl-umbelliferyl phosphate (4-MUP), there was a marked deficiency in ALP activity toward the natural substrates pyridoxal 5'-phosphate (PLP) and phosphoethanolamine (PEA), indicating altered substrate specificity. Furthermore, although 4-MUP phosphatase (4-MUP-P'tase) activity was predominantly localized as an ecto-enzyme, the small amount of PLP phosphatase (PLP-P'tase) activity was intracellular. This differential localization was apparent in intact cells, since (1) brief acidification of the medium at 4 degrees C inactivated a majority of the 4-MUP-P'tase activity but only 15% of the PLP-P'tase activity (in contrast to greater than 85% inactivation of both in homogenates), (2) greater than 70% of the 4-MUP-P'tase activity but only 30% of the PLP-P'tase activity was released by phosphatidylinositol-specific phospholipase C (PI-PLC) digestion, and (3) degradation of extracellular PLP was less than 35% of that of disrupted cells. Both 4-MUP- and PLP-P'tase activities were predominantly in a lipid-anchored form that could be converted to a soluble, lipid-free form by PI-PLC digestion. Our findings suggest that the clinical and biochemical presentation of this PSHPT patient results from the production of two aberrant ALP species. One form of ALP has appropriate ectoorientation but is preferentially deficient in activity toward natural substrates; the other ALP species has appropriate substrate specificity but is sequestered from substrates by its intracellular location.
 ...
PMID:Pseudohypophosphatasia: aberrant localization and substrate specificity of alkaline phosphatase in cultured skin fibroblasts. 217 30

1. Liver plasma membranes originating from the sinusoidal, lateral and canalicular surface domains of hepatocytes were covalently labelled with sulpho-N-hydroxysuccinamide-biotin. After solubilization in Triton X-114, treatment with a phosphatidylinositol-specific phospholipase C (PI-PLC), two-phase partitioning and 125I-streptavidin labelling of the proteins resolved by PAGE, six major polypeptides (molecular masses 110, 85, 70, 55, 38 and 35 kDa) were shown to be anchored in bile canalicular membrane vesicles by a glycosyl-phosphatidylinositol (G-PI) 'tail'. 2. Permeabilized 'early' and 'late' endocytic vesicles isolated from liver were also examined. Two polypeptides (110 and 35 kDa) were shown to be anchored by a G-PI tail in 'late' endocytic vesicles. 3. Analysis of marker enzymes in bile-canalicular vesicles treated with PI-PLC showed that 5'-nucleotidase and alkaline phosphatase, but not leucine aminopeptidase and ecto-Ca2(+)-ATPase activities were released from the membrane. A low release and recovery of alkaline phosphodiesterase activity was noted. The cleavage from the membrane of 5'-nucleotidase as a 70 kDa polypeptide was confirmed by Western blotting using an antibody to this enzyme. 4. Antibodies raised to proteins released from bile-canalicular vesicles by PI-PLC treatment, and purified by partitioning in aqueous and Triton X-114 phases, localized to the bile canaliculi in thin liver sections. Antibodies to proteins not hydrolysed by this treatment stained by immunofluorescence the sinusoidal and canalicular surface regions of hepatocytes. 5. Antibodies generated to proteins cleaved by PI-PLC treatment of canalicular vesicles were shown to identify, by Western blotting, a major 110 kDa polypeptide in these vesicles. Two polypeptides (55 and 38 kDa) were detected in MDCK and HepG-2 cultured cells. 6. Since two of the six G-PI-anchored proteins targeted to the bile-canalicular plasma membrane were also detected in 'late' endocytic vesicles, the results suggest that a junction where exocytic and endocytic traffic routes meet occurs in a 'late' endocytic compartment.
 ...
PMID:Priority targeting of glycosyl-phosphatidylinositol-anchored proteins to the bile-canalicular (apical) plasma membrane of hepatocytes. Involvement of 'late' endosomes. 217 97

Daily subcutaneous administration of 20 or 100 mg/kg gentamicin for 4 days significantly decreased pyridoxal-5'-phosphate and lysosomal specific phosphatidylinositol-phospholipase C (PI-PLC) in newborn rat kidney. The fall in PI-PLC was associated with an elevation in renal phosphatidylinositol, phosphatidylserine, and phosphatidylcholine. The 100 mg/kg gentamicin dose also produced a rise in renal sphingomyelin, phosphatidylethanolamine, phosphatidylglycerol, and total phospholipid (TPL) accompanied by inhibition in the activities of Na+,K+-ATPase and alkaline phosphatase. In contrast, daily intraperitoneal injection of 100 mg/kg vancomycin for 4 days failed to markedly alter renal metabolic parameters. However, the 500 mg/kg vancomycin dose increased kidney weight, TPL, and all individual phospholipid class concentrations accompanied by inhibition of lysosomal specific PI-PLC activity and reduced pyridoxal-5'-phosphate levels. Simultaneous administration of 20 mg/kg gentamicin with either vancomycin dose resulted in renal alterations similar to those produced by gentamicin alone. Concurrent treatment with 100 mg/kg aminoglycoside and either vancomycin dose produced changes in kidney which were similar to those produced by gentamicin alone, except for a synergistic rise in PI as well as a greater fall in alkaline phosphatase and pyridoxal-5'-phosphate. Surprisingly, the concentration of gentamicin and vancomycin was less in newborn kidneys of rats receiving a simultaneous high dose of vancomycin and aminoglycoside treatment compared to levels found in animals given either antibiotic separately. The lack of potentiation of nephrotoxicity in newborns administered a combination of vancomycin and gentamicin may be due to decreased accumulation of either antibiotic in kidney.
 ...
PMID:Gentamicin-induced renal metabolic alterations in newborn rat kidney: lack of potentiation by vancomycin. 252 10

1. We have compared the effect of phosphatidyl inositol specific phospholipase C (PI-PLC) on the attachment of both 5'-nucleotidase and alkaline phosphatase to the liver plasma membrane from different species. 2. Our results demonstrate differences in the susceptibilities of both enzymes to PI-PLC treatment in relation to their origin. 3. These results were confirmed by immunoblotting using polyclonal anti-5'-nucleotidase antibodies. 4. In addition, in a single animal, susceptibility of both enzymes to PI-PLC treatment is different from one tissue to another. 5. The different percentages of released enzymes could be explained either by a polymorphism in the anchoring of these proteins at the cell surface membrane, or by a different steric hindrance or environment at the cleavage site itself.
 ...
PMID:Differences in the release of 5'-nucleotidase and alkaline phosphatase from plasma membrane of several cell types by PI-PLC. 254 47

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.
 ...
PMID:5'-Nucleotide phosphodiesterase and alkaline phosphatase in tumor cells: evidence for existence of novel species in the cytosol. 283 40


1 2 3 4 Next >>